drm/i915/display/dp: Compute VRR state in atomic_check

This forces a complete modeset if vrr drm crtc state goes
from enabled to disabled and vice versa.
This patch also computes vrr state variables from the mode timings
and based on the vrr property set by userspace as well as hardware's
vrr capability.

v2:
*Rebase
v3:
* Vmin = max (vtotal, vmin) (Manasi)
v4:
* set crtc_state->vrr.enable = 0 for disable request
v5:
* drm_dbg_kms, squash crtc states def patch (Jani N)
v6:
* Move vrr modeset check to separate function (Jani N)
v7:
* Ville's fixes - vmin, vmax rename, fix rounding dir
* Add pipeline full, flipline to crtc state
* Pass conn state to vrr_compute_config (Ville)

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Jani Nikula <jani.nikula@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/20210122232647.22688-6-manasi.d.navare@intel.com