uboot-imx

MLK-20909 usb: dwc3: gadget: use usb_endpoint_maxp for req length

As endpoint.maxpackt is set at init for super speed, we can't use it
for USB2 connection, we need use the right max packet length according
to connection speed.

Signed-off-by: Li Jun <jun.li@nxp.com>
(cherry picked from commit 9c6bb3684649b4ae6f0275b5ad3799ea5c8f32df)