usb: chipidea: usbmisc: Add support for i.MX51 CPU

This adds i.MX51 as the next user of the usbmisc driver.
Functionality is similar to i.MX53, so at this stage simply
reuse existing i.MX53 calls.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>