hwc: Don't use MDP for buffers of width less than 5

This is a software workaround for MDP hardware limitation where
DSI mode panels wont give more than 30 FPS if buffers in RGB
pipes are of width less than 5

MDP can't handle layers of width less than 3. Fail MDP
Composition for those frames.

Change-Id: If45efab19817ea9e724fd2857fcc1c5d98ce0eab
diff --git a/libhwcomposer/hwc_mdpcomp.h b/libhwcomposer/hwc_mdpcomp.h
index 4dc5878..c953ec7 100644
--- a/libhwcomposer/hwc_mdpcomp.h
+++ b/libhwcomposer/hwc_mdpcomp.h
@@ -105,6 +105,8 @@
         struct PipeLayerPair* pipeLayer;
 
     };
+    /* checks for mdp comp width limitation */
+    bool isWidthValid(hwc_context_t *ctx, hwc_layer_1_t *layer);
     /* configure's overlay pipes for the frame */
     int configure(hwc_context_t *ctx, hwc_layer_1_t *layer,
                         MdpPipeInfo& mdp_info);