usb: typec: tcpci_maxim: Add support for Sink FRS

Upon receiving ALERT_EXTENDED.TCPC_SINK_FAST_ROLE_SWAP signal
tcpm to start Sink fast role swap signal.

Inform when TCPM is sourcing vbus.

Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20201008061556.1402293-9-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>