usb: chipidea: usbmisc_imx: add .set_wakeup interface

This API is used to enable/disable usb wakeup, only imx6 series are
added, since I don't have other imx hardware on hand. Other imx users
can add their API according to reference manual after testing.

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