Revert "USB: serial: sierra: put reset_resume callback back."

This reverts commit 6971113e.

As Alan pointed out, this really isn't needed as it doesn't handle this
properly.  Ideally this should be handled by the usb-serial core one
day.  So revert it.
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Johan Hovold <jhovold@gmail.com>
Cc: Anton Samokhvalov <pg83@yandex.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/sierra.c

@@ -1039,16 +1039,9 @@ static int sierra_resume(struct usb_serial *serial)
 	return ec ? -EIO : 0;
 }
 
-static int sierra_reset_resume(struct usb_serial *serial)
-{
-	dev_err(&serial->dev->dev, "%s\n", __func__);
-	return usb_serial_resume(serial->interface);
-}
-
 #else
 #define sierra_suspend NULL
 #define sierra_resume NULL
-#define sierra_reset_resume NULL
 #endif
 
 static struct usb_serial_driver sierra_device = {
@@ -1072,7 +1065,6 @@ static struct usb_serial_driver sierra_device = {
 	.release           = sierra_release,
 	.suspend	   = sierra_suspend,
 	.resume		   = sierra_resume,
-	.reset_resume	   = sierra_reset_resume,
 	.read_int_callback = sierra_instat_callback,
 };