drm/i915/vrr: Readout framestart_delay earlier

drm/i915/vrr: Readout framestart_delay earlier

In order to pretend that ICL/TGL VRR hardware has a similar guardband
as on ADL+ we'll need access to framestart_delay already during
intel_vrr_get_config(). Hoist the framestart_delay to an earlier point
to make that possible.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250917203446.14374-3-ville.syrjala@linux.intel.com
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>