drm/i915/: Extend VRR platform support to Gen 11

VRR is supported on Gen 11 HW , hence extend the support
in the driver to enable this for Gen 11.

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211116231209.28621-1-manasi.d.navare@intel.com