usb: typec: tcpm: Refactor logic to enable/disable auto vbus dicharge

usb: typec: tcpm: Refactor logic to enable/disable auto vbus dicharge

The logic to enable vbus auto discharge on disconnect is used in
more than one place. Since this is repetitive code, moving this into
its own method.

Fixes: f321a02caebd ("usb: typec: tcpm: Implement enabling Auto Discharge disconnect support")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Badhri Jagan Sridharan <badhri@google.com>
Link: https://lore.kernel.org/r/20210517192112.40934-2-badhri@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>