MLK-10015-2 Documentation: usb: chipidea: update for hnp_enable usage

Add documentation for how to use hnp_enable input file to enable or disable
full OTG HNP function in runtime.

Acked-by: Peter Chen <peter.chen@freescale.com>
Signed-off-by: Li Jun <jun.li@freescale.com>
(cherry picked from commit cd7a4868a63297e11a699b5f96f118df2bc9f437)
1 file changed