linux-imx

USB ehci mxc: sanitize clock handling

Every i.MX ehci controller has a ahb and a ipg clock, so request
it on every SoC. Do not make a special case for the usb phy clock
of the i.MX51. Just request it but make it optional.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>