drm/i915/dp: Add member to intel_dp to store AS SDP v2 support

drm/i915/dp: Add member to intel_dp to store AS SDP v2 support

eDP v1.5a advertises support for Adaptive Sync SDP and with that the
support for AS SDP v2 is mandatory.

DP v2.1 SCR advertises support for FAVT payload fields parsing in DPCD
0x2214 Bit 2. This indicates the support for Adaptive-Sync SDP version 2
(AS SDP v2), which allows the source to set the version in HB2[4:0] and the
payload length in HB3[5:0] of the AS SDP header.

DP v2.1 SCR also introduces ASYNC_VIDEO_TIMING_NOT_SUPPORTED_IN_PR in the
Panel Replay Capability DPCD 0x00b1 (Bit 3). When this bit is set, the sink
does not support asynchronous video timing while in a Panel Replay Active
state and the source is required to keep transmitting Adaptive-Sync
SDPs. The spec mandates that such sinks shall support AS SDP v2.

Infer AS SDP v2 support from these capabilities and store it in
struct intel_dp for use by subsequent feature enablement changes.

v2:
 - Include parsing ASYNC_VIDEO_TIMING_NOT_SUPPORTED_IN_PR bit to
   determine AS SDP v2 support. (Ville)
v3:
 - Use helper to determine asynch video timing support.
v4:
 - Add AS SDP v2 support for eDP as per v1.5a.
 - Add a check for Panel Replay support before checking for Async video
   timing support in PR
 - Add a TODO for Display ID and PCON considerations. (Ville)

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260527041050.601735-3-ankit.k.nautiyal@intel.com