usg: gadget: Move validation out of lock in webusb_bcdVersion_store()

Validation has nothing to do with any protected data,
move it out of the lock and make code neater.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20230127112638.84806-1-andriy.shevchenko@linux.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>