PM: Disable usb host HW save and restore

The hardware SAVEANDRESTORE mechanism seems to leave
USB HOST power domain permanently into active state
after one transition from off to active state.
Disabling for now.

Signed-off-by: Kalle Jokiniemi <ext-kalle.jokiniemi@nokia.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>