Enable Gralloc ion sync

Gralloc ion sync enables a cache sync when Gralloc buffers are
unlocked.  Buffers the GPU wrote don't need this, but buffers the
CPU wrote do.

Bug: 183735780
Test: RealCalc
Change-Id: I67a9ee15b172fb11d262c41723404c5b9cafde82
diff --git a/BoardConfig-common.mk b/BoardConfig-common.mk
index 607e56f..ff5b93d 100644
--- a/BoardConfig-common.mk
+++ b/BoardConfig-common.mk
@@ -90,6 +90,7 @@
 BOARD_USES_EXYNOS5_COMMON_GRALLOC := true
 BOARD_USES_EXYNOS_GRALLOC_VERSION := $(DEVICE_USES_EXYNOS_GRALLOC_VERSION)
 BOARD_USES_ALIGN_RESTRICTION := false
+BOARD_USES_GRALLOC_ION_SYNC := true
 
 # This should be the same value as USE_SWIFTSHADER in device.mk
 BOARD_USES_SWIFTSHADER := false