drm/i915/hdcp: Rename comp_mutex to hdcp_mutex

Rename comp_mutex to hdcp_mutex as it does not just
protect component related variables which was a terminology
used when hdcp was to be binded as a mei component from MTL
we use gsc cs which does not use the component binding path
for HDCP.

Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230529110740.1522985-4-suraj.kandpal@intel.com