usb:ci_udc: Remove ULPI setting for i.MX OTG controller

All the i.MX6, i.MX23 and i.MX28 OTG controllers only support UTMI
interface. Set to ULPI is not correct, even the controller will
reject this setting in PORTSC register.

Signed-off-by: Ye.Li <B37916@freescale.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>