drm/i915/gsc: Create GSC request submission mechanism

HDCP and PXP will require a common function to allow it to
submit commands to the gsc cs. Also adding the gsc mtl header
that needs to be added on to the existing payloads of HDCP
and PXP.

--v4
-Seprate gsc load and heci cmd submission into different
functions in different files for better scalability [Alan]
-Rename gsc address field [Alan]

--v5
-remove extra line is intel_gsc_fw.h [Uma]

Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Signed-off-by: Suraj <Kandpal&lt;suraj.kandpal@intel.com>
Reviewed-by: Alan Previn <alan.previn.teres.alexis@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/20230316092927.668980-2-suraj.kandpal@intel.com