usb: chipidea: debug: add debug file for controller registers dump

This patch adds below registers dump for debug:
- USBINTR
- USBSTS
- USBMODE
- USBCMD
- PORTSC
- OTGSC

Signed-off-by: Peter Chen <peter.chen@freescale.com>
Acked-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Li Jun <b47624@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>