drm/i915/hdcp: Move source hdcp2 checks into its own function

Move checks on the source side for HDCP2.2 into its own function
so that they can be used in the HDCP remote capability check
function.

Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240223081453.1576918-4-suraj.kandpal@intel.com