usb: typec: Make bus switch code retimer-aware

usb: typec: Make bus switch code retimer-aware

Since ports can have retimers associated with them, update the Type-C
alternate mode bus code to also set retimer state when the switch state
is updated.

While we are here, make the typec_retimer_dev_type declaration in the
retimer.h file as extern, so that the header file can be successfully
included in the bus code without redeclaration compilation errors.

Signed-off-by: Prashant Malani <pmalani@chromium.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Link: https://lore.kernel.org/r/20230112221609.540754-4-pmalani@chromium.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>