usb: gadget: s3c-hsudc: remove unused label

Fixes the following compilation warning:
drivers/usb/gadget/s3c-hsudc.c: In function ‘s3c_hsudc_probe’:
drivers/usb/gadget/s3c-hsudc.c:1347:1: warning: label ‘err_add_device’
defined but not used [-Wunused-label]

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>