drm/sprd: add Unisoc's drm mipi dsi&dphy driver

Adds dsi host controller support for the Unisoc's display subsystem.
Adds dsi phy support for the Unisoc's display subsystem.
Only MIPI DSI Displays supported, DP/TV/HMDI will be support
in the feature.

Cc: Orson Zhai <orsonzhai@gmail.com>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Signed-off-by: Kevin Tang <kevin3.tang@gmail.com>

drivers/gpu/drm/sprd/Makefile

@@ -1,7 +1,12 @@
 # SPDX-License-Identifier: GPL-2.0
 
 obj-y := sprd_drm.o \
-	sprd_dpu.o
+	sprd_dpu.o \
+	sprd_dsi.o \
+	sprd_dphy.o \
+	dpu_r2p0.o \
+	dw_dsi_ctrl.o \
+	dw_dsi_ctrl_ppi.o \
+	megacores_pll.o
 
-obj-y += dpu_r2p0.o