usb: gadget: s3c: Remove unused 'udc' variable

Remove unused 'udc' variable to fix compile warnings:

    drivers/usb/gadget/udc/s3c2410_udc.c: In function 's3c2410_udc_dequeue':
    drivers/usb/gadget/udc/s3c2410_udc.c:1268:22: warning: variable 'udc' set but not used [-Wunused-but-set-variable]

Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Felipe Balbi <balbi@kernel.org>