usb: gadget: udc: mv_udc_core: Remove unused static const variable 'driver_desc'

Looks as though it's never been used. Driver was introduced in 2014.

Fixes the following W=1 kernel build warning(s):

drivers/usb/gadget/udc/mv_udc_core.c:56:19: warning: ‘driver_desc’ defined but not used [-Wunused-const-variable=]
56 | static const char driver_desc[] = DRIVER_DESC;
| ^~~~~~~~~~~

Cc: Felipe Balbi <[e-mail]>
Cc: Chao Xie <[e-mail]>
Cc: Neil Zhang <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/gadget/udc/mv_udc_core.c

···
 static DECLARE_COMPLETION(release_done);
 
 static const char driver_name[] = "mv_udc";
-static const char driver_desc[] = DRIVER_DESC;
 
 static void nuke(struct mv_ep *ep, int status);
 static void stop_activity(struct mv_udc *udc, struct usb_gadget_driver *driver);