usb: gadget: udc: make udc-core compile in u-boot build

Make udc-core compile in u-boot by removing all linux specific
stuff and having only the bare minimal udc-core required for
usb gadget drivers. Also modified the file header to a format that is
generally being used in u-boot.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Reviewed-by: Lukasz Majewski <l.majewski@samsung.com>
1 file changed