media: dvb-usb: Replace GFP_ATOMIC with GFP_KERNEL

Despite never getting called from atomic context,
usb URB memory allocations use GFP_ATOMIC, which does not sleep
for allocation.

GFP_ATOMIC is not necessary and can be replaced with GFP_KERNEL,
which can sleep and improve the possibility of sucessful allocation.

This is found by a static analysis tool named DCNS written by myself.
And I also manually check it.

[mchehab+samsung@kernel.org: merged 3 similar patches into one]
Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/dvb-usb/usb-urb.c

@@ -118,7 +118,7 @@ static int usb_allocate_stream_buffers(struct usb_data_stream *stream, int num,
 	for (stream->buf_num = 0; stream->buf_num < num; stream->buf_num++) {
 		deb_mem("allocating buffer %d\n",stream->buf_num);
 		if (( stream->buf_list[stream->buf_num] =
-					usb_alloc_coherent(stream->udev, size, GFP_ATOMIC,
+					usb_alloc_coherent(stream->udev, size, GFP_KERNEL,
 					&stream->dma_addr[stream->buf_num]) ) == NULL) {
 			deb_mem("not enough memory for urb-buffer allocation.\n");
 			usb_free_stream_buffers(stream);
@@ -145,7 +145,7 @@ static int usb_bulk_urb_init(struct usb_data_stream *stream)
 
 	/* allocate the URBs */
 	for (i = 0; i < stream->props.count; i++) {
-		stream->urb_list[i] = usb_alloc_urb(0, GFP_ATOMIC);
+		stream->urb_list[i] = usb_alloc_urb(0, GFP_KERNEL);
 		if (!stream->urb_list[i]) {
 			deb_mem("not enough memory for urb_alloc_urb!.\n");
 			for (j = 0; j < i; j++)
@@ -178,7 +178,7 @@ static int usb_isoc_urb_init(struct usb_data_stream *stream)
 		struct urb *urb;
 		int frame_offset = 0;
 
-		stream->urb_list[i] = usb_alloc_urb(stream->props.u.isoc.framesperurb, GFP_ATOMIC);
+		stream->urb_list[i] = usb_alloc_urb(stream->props.u.isoc.framesperurb, GFP_KERNEL);
 		if (!stream->urb_list[i]) {
 			deb_mem("not enough memory for urb_alloc_urb!\n");
 			for (j = 0; j < i; j++)