drm/msm/sde: separate plane/encoder/crtc functions into headers

Currently, plane/encoder/crtc function prototypes reside in the
kms header. To improve code separation and reduce overlap changes,
separate plane/encoder/crtc functions from kms header into their
corresponding headers.

Change-Id: Id3a7098ada887538ac0635f381c553a516237e7a
Signed-off-by: Alan Kwong <akwong@codeaurora.org>
diff --git a/drivers/gpu/drm/msm/sde/sde_plane.c b/drivers/gpu/drm/msm/sde/sde_plane.c
index e11a797..ee98bb0 100644
--- a/drivers/gpu/drm/msm/sde/sde_plane.c
+++ b/drivers/gpu/drm/msm/sde/sde_plane.c
@@ -24,6 +24,7 @@
 #include "sde_trace.h"
 #include "sde_crtc.h"
 #include "sde_vbif.h"
+#include "sde_plane.h"
 
 #define SDE_DEBUG_PLANE(pl, fmt, ...) SDE_DEBUG("plane%d " fmt,\
 		(pl) ? (pl)->base.base.id : -1, ##__VA_ARGS__)