drm/i915: Introduce intel_psr.c

No functional changes. Just cleaning and reorganizing it.

v2: Rebase it puting it to begin of psr rework. This helps to blame easily
at least latest changes.

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_ddi.c b/drivers/gpu/drm/i915/intel_ddi.c
index ca33ee9..3e4c63c 100644
--- a/drivers/gpu/drm/i915/intel_ddi.c
+++ b/drivers/gpu/drm/i915/intel_ddi.c
@@ -1583,7 +1583,7 @@
 			intel_dp_stop_link_train(intel_dp);
 
 		intel_edp_backlight_on(intel_dp);
-		intel_edp_psr_enable(intel_dp);
+		intel_psr_enable(intel_dp);
 	}
 
 	if (intel_crtc->config.has_audio) {
@@ -1609,7 +1609,7 @@
 	if (type == INTEL_OUTPUT_EDP) {
 		struct intel_dp *intel_dp = enc_to_intel_dp(encoder);
 
-		intel_edp_psr_disable(intel_dp);
+		intel_psr_disable(intel_dp);
 		intel_edp_backlight_off(intel_dp);
 	}
 }