drm/i915: add basic MIPI DSI output support

This does not include any panel specific sub-encoders yet.

v2: Fix fixed mode handling (Daniel)

v3: Mostly based on Ville's review comments.
 - Fix MIPI_HS_TX_TIMEOUT.
 - DPI_ENABLE only for video mode.
 - Drop ULPS usage for now, use DEVICE_READY only.
 - Set MIPI_INIT_COUNT based on txclkesc.

Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 8bffd29..5864c5b 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -21,6 +21,7 @@
 	  intel_display.o \
 	  intel_crt.o \
 	  intel_lvds.o \
+	  intel_dsi.o \
 	  intel_dsi_cmd.o \
 	  intel_bios.o \
 	  intel_ddi.o \