drm/i915/display/vrr: Create VRR file and add VRR capability check

We create a new file for all VRR related helpers.
Also add a function to check vrr capability based on
platform support, DPCD bits and EDID monitor range.

v2:
* Remove author (Jani N)
* Define HAS_VRR (Jani N)
* Ensure intel_dp can be obtained from conn (Jani N)

v3:
* Fix the header indent (Manasi)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@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/20210125200818.2015-1-manasi.d.navare@intel.com