drm/i915: move modesetting output/encoder code under display/

Add a new subdirectory for display code, and start off by moving
modesetting output/encoder code. Judging by the include changes, this is
a surprisingly clean operation.

v2:
- move intel_sdvo_regs.h too
- use tabs for Makefile	file lists and sort them

Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Acked-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Acked-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190613084416.6794-2-jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_vdsc.h

@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: MIT */
+/*
+ * Copyright © 2019 Intel Corporation
+ */
+
+#ifndef __INTEL_VDSC_H__
+#define __INTEL_VDSC_H__
+
+struct intel_encoder;
+struct intel_crtc_state;
+struct intel_dp;
+
+void intel_dsc_enable(struct intel_encoder *encoder,
+		      const struct intel_crtc_state *crtc_state);
+void intel_dsc_disable(const struct intel_crtc_state *crtc_state);
+int intel_dp_compute_dsc_params(struct intel_dp *intel_dp,
+				struct intel_crtc_state *pipe_config);
+enum intel_display_power_domain
+intel_dsc_power_domain(const struct intel_crtc_state *crtc_state);
+
+#endif /* __INTEL_VDSC_H__ */