usb: gadget: Use correct endianness of the wLength field for WebUSB

WebUSB code uses wLength directly without proper endianness conversion.
Update it to use already prepared temporary variable w_length instead.

Fixes: 93c47394 ("usb: gadget: add WebUSB landing page support")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-By: Jó Ágila Bitsch <jgilab@gmail.com>
Link: https://lore.kernel.org/r/20230313154522.52684-1-andriy.shevchenko@linux.intel.com


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