[media] easycap: Fix mem leak in easycap_usb_probe()

If allocating 'pdata_urb' fails, the function will return -ENOMEM
without freeing the memory allocated, just a few lines above, for
'purb' and will leak that memory when 'purb' goes out of scope.

This patch resolves the leak by freeing the allocated storage with
usb_free_urb() before the return.
Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/staging/media/easycap/easycap_main.c

@@ -3825,6 +3825,7 @@ static int easycap_usb_probe(struct usb_interface *intf,
 /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
 			pdata_urb = kzalloc(sizeof(struct data_urb), GFP_KERNEL);
 			if (!pdata_urb) {
+				usb_free_urb(purb);
 				SAM("ERROR: Could not allocate struct data_urb.\n");
 				return -ENOMEM;
 			}