usb: typec: altmodes/displayport: Fall back to multi-func pins

If our port-partner supports both DP-only operation (pin-assignment C)
and multi-func operation (pin-assignment D) and we only support
pin-assignment D and the port-partner prefers DP-only mode, then
before this commit we would and up masking out pin-assignment D from
the available pin-assignments and fail to pick a pin-assignment.

Instead only mask out the multi-func pin-assignments if we support
dp-only pin-assignments, so that we correctly fall-back to a multi-func
pin-assignment in this case (by picking pin-assignment D).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>