drm/xe/display/xe_hdcp_gsc: Free arbiter on driver removal

drm/xe/display/xe_hdcp_gsc: Free arbiter on driver removal

Free arbiter allocated in intel_hdcp_gsc_init().

Fixes: 152f2df954d8 ("drm/xe/hdcp: Enable HDCP for XE")
Cc: Suraj Kandpal <suraj.kandpal@intel.com>
Cc: Arun R Murthy <arun.r.murthy@intel.com>
Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240708125918.23573-1-nirmoy.das@intel.com
Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>