usb: gadget: dfu: Fix the unchecked length field

DFU implementation does not bound the length field in USB
DFU download setup packets, and it does not verify that
the transfer direction. Fixing the length and transfer
direction.

CVE-2022-2347

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Reviewed-by: Marek Vasut <marex@denx.de>