usb: core: update comments for send message functions

The commonly use of bottom halves are tasklet and workqueue. The big
difference between tasklet and workqueue is that the tasklet runs in
an interrupt context and the workqueue runs in a process context,
which means it can sleep if need be.

The comment for usb_control/interrupt/bulk_msg() functions note that do
not use this function within an interrupt context, like a 'bottom half'
handler. With this comment, it makes confuse about usage of these
functions.

To more clarify, remove 'bottom half' comment.
Signed-off-by: Jaejoong Kim <climbbb.kim@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/message.c

@@ -122,12 +122,11 @@ static int usb_internal_control_msg(struct usb_device *usb_dev,
  * This function sends a simple control message to a specified endpoint and
  * waits for the message to complete, or timeout.
  *
- * Don't use this function from within an interrupt context, like a bottom half
- * handler.  If you need an asynchronous message, or need to send a message
- * from within interrupt context, use usb_submit_urb().
- * If a thread in your driver uses this call, make sure your disconnect()
- * method can wait for it to complete.  Since you don't have a handle on the
- * URB used, you can't cancel the request.
+ * Don't use this function from within an interrupt context. If you need
+ * an asynchronous message, or need to send a message from within interrupt
+ * context, use usb_submit_urb(). If a thread in your driver uses this call,
+ * make sure your disconnect() method can wait for it to complete. Since you
+ * don't have a handle on the URB used, you can't cancel the request.
  *
  * Return: If successful, the number of bytes transferred. Otherwise, a negative
  * error number.
@@ -173,12 +172,11 @@ EXPORT_SYMBOL_GPL(usb_control_msg);
  * This function sends a simple interrupt message to a specified endpoint and
  * waits for the message to complete, or timeout.
  *
- * Don't use this function from within an interrupt context, like a bottom half
- * handler.  If you need an asynchronous message, or need to send a message
- * from within interrupt context, use usb_submit_urb() If a thread in your
- * driver uses this call, make sure your disconnect() method can wait for it to
- * complete.  Since you don't have a handle on the URB used, you can't cancel
- * the request.
+ * Don't use this function from within an interrupt context. If you need
+ * an asynchronous message, or need to send a message from within interrupt
+ * context, use usb_submit_urb() If a thread in your driver uses this call,
+ * make sure your disconnect() method can wait for it to complete. Since you
+ * don't have a handle on the URB used, you can't cancel the request.
  *
  * Return:
  * If successful, 0. Otherwise a negative error number. The number of actual
@@ -207,12 +205,11 @@ EXPORT_SYMBOL_GPL(usb_interrupt_msg);
  * This function sends a simple bulk message to a specified endpoint
  * and waits for the message to complete, or timeout.
  *
- * Don't use this function from within an interrupt context, like a bottom half
- * handler.  If you need an asynchronous message, or need to send a message
- * from within interrupt context, use usb_submit_urb() If a thread in your
- * driver uses this call, make sure your disconnect() method can wait for it to
- * complete.  Since you don't have a handle on the URB used, you can't cancel
- * the request.
+ * Don't use this function from within an interrupt context. If you need
+ * an asynchronous message, or need to send a message from within interrupt
+ * context, use usb_submit_urb() If a thread in your driver uses this call,
+ * make sure your disconnect() method can wait for it to complete. Since you
+ * don't have a handle on the URB used, you can't cancel the request.
  *
  * Because there is no usb_interrupt_msg() and no USBDEVFS_INTERRUPT ioctl,
  * users are forced to abuse this routine by using it to submit URBs for