hwc: Set default idle timeout to 70ms

Set default idle timeout to 70ms (~4 cycles on 60fps panel + some extra)
from the earlier 2sec.
The GPU timeout is around 80ms after which it turns off its rail,
clock and bus vote. So having a draw cycle before that is beneficial

Change-Id: I03291a4b8fd0707839567987febe1c088e21c92d
diff --git a/libhwcomposer/hwc_mdpcomp.h b/libhwcomposer/hwc_mdpcomp.h
index 05a560b..512a120 100644
--- a/libhwcomposer/hwc_mdpcomp.h
+++ b/libhwcomposer/hwc_mdpcomp.h
@@ -25,7 +25,7 @@
 #include <cutils/properties.h>
 #include <overlay.h>
 
-#define DEFAULT_IDLE_TIME 2000
+#define DEFAULT_IDLE_TIME 70
 #define MAX_PIPES_PER_MIXER 4
 
 namespace overlay {