drm/msm/dsi: Add a mdp4 encoder for DSI

Create an mdp4 incoder for DSI. Only DSI video mode is supported as of
now.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
Signed-off-by: Vinay Simha BN <vinaysimha@inforcecomputing.com>
Signed-off-by: Rob Clark <robdclark@gmail.com>

drivers/gpu/drm/msm/Makefile

@@ -54,6 +54,7 @@ msm-$(CONFIG_DRM_FBDEV_EMULATION) += msm_fbdev.o
 msm-$(CONFIG_COMMON_CLK) += mdp/mdp4/mdp4_lvds_pll.o
 
 msm-$(CONFIG_DRM_MSM_DSI) += dsi/dsi.o \
+			mdp/mdp4/mdp4_dsi_encoder.o \
 			dsi/dsi_cfg.o \
 			dsi/dsi_host.o \
 			dsi/dsi_manager.o \