usb: typec: tcpm: Handle vbus shutoff when in source mode

usb: typec: tcpm: Handle vbus shutoff when in source mode

While in source mode, vbus could be shutoff by protections
circuits. TCPM does not move back to toggling state to
re-initiate connection. Fix this by moving to SRC_UNATTACHED
state when vbus shuts off while in source mode.

Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20210201100212.49863-1-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>