usb: chipidea: imx: enable OTG overcurrent in case USB subsystem is already started

When initializing the USB subsystem before starting the kernel,
OTG overcurrent detection is disabled. In case the OTG polarity of
overcurrent is low active, the overcurrent detection is never enabled
again and events cannot be reported as expected. Because imx usb
overcurrent polarity is low active by default, only detection needs
to be enable in usbmisc init function.

Signed-off-by: Nicolas Adell <nicolas.adell@actia.fr>
Signed-off-by: Peter Chen <peter.chen@nxp.com>