USB: fsl_usb2_udc: fix bug in processing setup requests

Kim Liu found that in the original code certain class setup requests
are wrongly recognized and processed as standard setup requests.
For that reason gadget ether can't work in RNDIS mode with Windows host.

The patch fixes the setup request processing code, and makes class
requests correctly passed to gadget layer.

Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Kim Liu <KLiu@vixs.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>