drm/i915/vrr: Compute vrr.vsync_{start, end} during full modeset

vrr.vsync_{start,end} computation should not depend on
crtc_state->vrr.enable.

--v1:
 - Explain commit message more clearly [Jani]
 - Instead of tweaking to fastset use vrr.flipline while computing AS_SDP.
--v2:
 - Correct computation of vrr.vsync_start/end should not depend on
   vrr.enable.[ville]
 - vrr enable disable requirement should not obstruct by SDP enable
   disable requirements. [Ville]
--v3:
 - Create separate patch for crtc_state_dump [Ankit].

--v4:
 - Update commit message and header [Ankit].

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/20250130051609.1796524-3-mitulkumar.ajitkumar.golani@intel.com