USB OTG Langwell: use simple IPC command to control VBus power.

Direct access to PMIC register is not safe and will impact battery
charging. New IPC command supported in SCU FW for VBus power control.
USB OTG driver will switch to such commands instead of direct access
to PMIC register for safety and SCU FW will handle the actual work
after got the request(IPC command).

Due to this change, usb driver should wait more time for sync OTGSC
with USBCFG by SCU. Update wait time from 2ms to 5ms.

Signed-off-by: Hao Wu <hao.wu@intel.com>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>