drm/i915/hdcp: Create force_hdcp14 debug fs entry

drm/i915/hdcp: Create force_hdcp14 debug fs entry

Testing HDCP 1.4 becomes tough since the only way our code comes to
HDCP 1.4 pathway is if the monitor only supports HDCP 1.4 which
becomes tough to find sometimes.
Setting this debug_fs entry will force use to use the HDCP 1.4 path
so that more robust HDCP 1.4 testing can take place.

--v2
-Move the code to intel_hdcp.c [Jani]
-Remove useless debug logging [Jani]
-Remove Force_HDCP from the debug file [Jani]

--v3
-Remove leftover debug loggings [Jani]

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250213082541.3772212-1-suraj.kandpal@intel.com