usb: chipidea: debug: add debug file for OTG variables

This patch adds a debug file for OTG vairables show.

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