drm/i915/display: Move vrr.guardband/pipeline_full out of !fastset block

drm/i915/display: Move vrr.guardband/pipeline_full out of !fastset block

Since the vrr.guardband can now change for platforms that always use the
VRR Timing Generator, and it is unsafe to reprogram the guardband on the
fly, move the guardband and pipeline_full checks from the pure !fastboot
path and add a check for intel_vrr_always_use_vrr_tg().

For older platforms the vrr.guardband change happens when VRR Timing
generator is off. For the platforms that always use the VRR Timing
Generator, this will prevent reprogramming the vrr.guardband without a
full modeset. However, this will disrupt LRR functionality for these
platforms.

v2: Modify the check to avoid breaking the LRR on older platform.
(Ville)
v3: Correct the oversight of not removing the lines from the original
location. (Ville)

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/20250324133248.4071909-12-ankit.k.nautiyal@intel.com