drm/i915/display: Renaming DRRS functions to intel_drrs_*()

drm/i915/display: Renaming DRRS functions to intel_drrs_*()

We had a mix of intel_edp_drrs_*(), intel_dp_drrs_*() and
intel_dp_set_drrs_state(), so properly renaming all functions to
keep the same pattern.

While at it, also dropping intel_dp_set_drrs_state from the
documentation as it is a static function.

v3:
- dropping documentation style comment in static function
(intel_drrs_set_state)

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210827174253.51122-3-jose.souza@intel.com