usb: typec: Prepare alt mode enter/exit reporting for UCSI alt mode support

Because of UCSI, we have to support alt mode enter/exit
reporting even when there is no alt mode driver bind to the
alt mode device. With UCSI a firmware handles the alternate
modes, and the modes are entered automatically from OS PoW.

Changing typec_altmode_update_active() so that the driver
module ref count is incremented/decremented only if there
really is a driver for the alt mode. That avoids a NULL
pointer dereference from happening when the driver is
missing.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>