drm/i915/vrr: Add functions to read out vmin/vmax stuff

drm/i915/vrr: Add functions to read out vmin/vmax stuff

Calculate delayed vblank start position with the help of added
vmin/vmax stuff for next frame and final computation.

--v2:
- Correct Author details.

--v3:
- Separate register details from this  patch.

--v4:
- Add mask macros.

--v5:
- As live prefix params indicate timings for current frame,
read just _live prefix values instead of next frame timings as
done previously.
- Squash Refactor vrr params patch.

--v6:
- Use error code while returning invalid values. (Jani, Nikula)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://patch.msgid.link/20251223104542.2688548-5-mitulkumar.ajitkumar.golani@intel.com