drm/i915/vrr: Set trans_vrr_ctl in intel_vrr_set_transcoder_timings()

drm/i915/vrr: Set trans_vrr_ctl in intel_vrr_set_transcoder_timings()

We now always set vrr.flipline, vmin, and vmax for all platforms that
support VRR. Therefore, we should set all TRANS_VRR_CTL bits except
VRR_ENABLE. Without this, the readback for these bits will fail because we
only read vrr.flipline, vmin, and vmax if TRANS_VRR_CTL has the
FLIPLINE_EN bit set.

For platforms that always have the VRR Timing Generator enabled,
the FLIPLINE_EN bit is always set in TRANS_VRR_CTL during
intel_transcoder_vrr_enable(). However, for the remaining platforms
(that do not always have the VRR Timing Generator enabled) if a full
modeset doesn't occur and VRR is not enabled, the bit is not set.

This results in a mismatch between the software state and hardware state
because the software state expects VRR timings like flipline, vmin, and
vmax to be set, but the readout for these doesn't happen since the
FLIPLINE_EN bit is not set in TRANS_VRR_CTL.

To avoid this mismatch, write trans_vrr_ctl in
intel_vrr_set_transcoder_timings() even when VRR is not enabled
for platforms that do not have the VRR Timing Generator always enabled.

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/20250324133248.4071909-15-ankit.k.nautiyal@intel.com