usb:udc:samsung:fix Remove the req_config flag

The dev->req_config flag was indicating that the forwarded
request needs to perform the usb gadget delayed status.
This is however not needed anymore, so it can be removed.

Signed-off-by: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Marek Vasut <marex@denx.de>