Add hooks to intel_digital_port to lock and unlock the port and add a
helper to check the connector's detect status while the port is locked
already. This simplifies checking the connector detect status in
intel_dp_aux_xfer() and intel_digital_port_connected() in the next two
patches aborting AUX transfers on all DP connectors (except eDP) and
filtering HPD glitches.

Link: https://patchwork.freedesktop.org/patch/msgid/20240104083008.2715733-11-imre.deak@intel.comReviewed-by: Jouni Högander <jouni.hogander@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>