USB: EHCI: Add Intel Moorestown EHCI controller HOSTPCx extensions and support phy low power mode

The Intel Moorestown EHCI controller supports non-standard HOSTPCx register
extension. This register controls the LPM behaviour and controls the behaviour
of each USB port.

Signed-off-by: Jacob Pan <jacob.jun.pan@intel.com>
Signed-off-by: Alek Du <alek.du@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>