fsl_usb2_udc: Make dr_ep_setup function static.

Make dr_ep_setup function static as it's never used outside this file.

Signed-off-by: Will Newton <will.newton@gmail.com>
Acked-by: Li Yang <leoli@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>