drm/i915/display: Drop intel_vrr_vblank_delay and use set_context_latency

drm/i915/display: Drop intel_vrr_vblank_delay and use set_context_latency

The helper intel_vrr_vblank_delay() was used to keep track of the SCL
lines + the extra vblank delay required for ICL/TGL.
This was used to wait for sufficient lines for:
-push send bit to clear for VRR case
-evasion to delay the commit.

For first case we are using safe window scanline wait and with that we
just need to wait for SCL lines, we do not need to wait for the extra
vblank delay required for ICL/TGL. For the second case, we actually
do not need to wait for extra lines before the undelayed vblank, if we
are already in the safe window.

To sum up, SCL lines is sufficient for both cases.

So drop the helper intel_vrr_vblank_delay and just use
crtc_state->set_context_latency instead.

Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://lore.kernel.org/r/20250924141542.3122126-10-ankit.k.nautiyal@intel.com