drm/i915/dp: Add wrapper function to check AS SDP

Add a wrapper function to check if both the source and
sink support Adaptive Sync SDP.

--v1:
Just use drm/i915/dp in subject line.

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@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/20240322031157.3823909-6-mitulkumar.ajitkumar.golani@intel.com