usb: typec: ucsi: Store the notification mask

The driver needs to ignore any Connector Change Events
before the Connector Change Indication notifications have
actually been enabled. This adds a check to
ucsi_connector_change() function to make sure the function
does not try to process the event unless the Connector
Change notifications have been enabled.

It is quite common that the firmware representing the "PPM"
(Platform Policy Manager) starts generating Connector Change
notifications even when only the Command Completion
notifications are enabled.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20191230133431.63445-2-heikki.krogerus@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>