drm/i915/mtl: Add HDCP GSC interface

MTL uses GSC command streamer i.e gsc cs to send HDCP/PXP commands
to GSC f/w. It requires to keep hdcp display driver
agnostic to content protection f/w (ME/GSC fw) in the form of
i915_hdcp_fw_ops generic ops.

Adding HDCP GSC CS interface by leveraging the i915_hdcp_fw_ops generic
ops instead of I915_HDCP_COMPONENT as integral part of i915.

Adding checks to see if GSC is loaded and proxy is setup

--v6
-dont change the license date in same patch series [Jani]
-fix the license year {Jani]

--v8
-remove stale comment [Ankit]
-get headers in alphabetical order [Ankit]
-fix hdcp2_supported check [Ankit]

--v9
-remove return statement from hdcp_gsc_fini [Ankit]

Cc: Tomas Winkler <tomas.winkler@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230316092927.668980-7-suraj.kandpal@intel.com