libhwcomposer: Reset composition types on idle timeout.

SurfaceFlinger re-creates HWC worklist only for new frame and on layer geometry
change. Invalidate triggered by idle timeout refreshes the existing worklist
retaining its previous composition type. So its MDP comp's responsibility to
clear layer composition types to HWC_FRAMEBUFFER on timeout.

Change-Id: I2407c44f6aa3b11365586364e5865ae629d5326a
diff --git a/libhwcomposer/hwc_mdpcomp.h b/libhwcomposer/hwc_mdpcomp.h
index 5cb2476..53c85da 100644
--- a/libhwcomposer/hwc_mdpcomp.h
+++ b/libhwcomposer/hwc_mdpcomp.h
@@ -181,7 +181,7 @@
 
     /* checks for conditions where mdpcomp is not possible */
     static bool is_doable(hwc_composer_device_1_t *dev,
-                           const hwc_display_contents_1_t* list);
+                          hwc_display_contents_1_t* list);
 
     static bool setup(hwc_context_t* ctx, hwc_display_contents_1_t* list);