usb: gadget: f_fs: remove unneeded semicolon in __ffs_data_got_descs()

Fix the following coccicheck warning:

drivers/usb/gadget/function/f_fs.c:2507:2-3: Unneeded semicolon

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>