usb: gadget: dfu: Fix check of transfer direction

Commit fbce985e to fix CVE-2022-2347
blocks DFU usb requests.
The verification of the transfer direction was done by an equality
but it is a bit mask.

Signed-off-by: Hugo SIMELIERE <hsimeliere.opensource@witekio.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>
Reviewed-by: Sultan Qasim Khan <sultan.qasimkhan@nccgroup.com>
Reviewed-by: Marek Vasut <marex@denx.de>
Tested-by: Marek Vasut <marex@denx.de>