usb: image: mdc800: Remove redundant assignment to variable retval

The variable retval is being assigned a value that is not being read
and is being re-assigned a new value a couple of statements later.
The assignment is redundant and can be removed.

Cleans up clang scan warning:
drivers/usb/image/mdc800.c:634:2: warning: Value stored to 'retval'
is never read [deadcode.DeadStores]
Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20240207113730.2444296-1-colin.i.king@gmail.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/image/mdc800.c

@@ -631,7 +631,6 @@ static int mdc800_device_open (struct inode* inode, struct file *file)
 	mdc800->camera_busy=0;
 	mdc800->camera_request_ready=0;
 
-	retval=0;
 	mdc800->irq_urb->dev = mdc800->dev;
 	retval = usb_submit_urb (mdc800->irq_urb, GFP_KERNEL);
 	if (retval) {