USB: i.MX5x: Remove usage of MXC_EHCI_INTERNAL_PHY for OTG port
i.MX5x OTG port is hardwired to the internal UTMI PHY, so having
this configurable makes no sense and helps using this port with DT.
Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>