drm/i915: Stash DRRS state under intel_crtc

Ger rid of one more ugly crtc->config usage by storing the DRRS
state under intel_crtc. intel_drrs_enable() copies what it needs
from the crtc state, after which DRRS can be blissfully ignorant
of anything going on around it.

This also lets multiple pipes do DRRS simultanously and entirely
independently.

v2: Split out some stuff (Jani)

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220311172428.14685-13-ville.syrjala@linux.intel.com


Reviewed-by: Jani Nikula <jani.nikula@intel.com>