mm-video-legacy: vdec: force uncached gralloc buffers

as CPU may access these buffers

Bug: 17906609
Change-Id: I1b4c711e3ba3d0a1888ac12b0b759da5014b44b5
diff --git a/mm-video-legacy/vidc/vdec/src/omx_vdec.cpp b/mm-video-legacy/vidc/vdec/src/omx_vdec.cpp
index ccb3f7a..f47702d 100644
--- a/mm-video-legacy/vidc/vdec/src/omx_vdec.cpp
+++ b/mm-video-legacy/vidc/vdec/src/omx_vdec.cpp
@@ -2915,7 +2915,7 @@
                         nativeBuffersUsage->nUsage = (GRALLOC_USAGE_PRIVATE_MM_HEAP | GRALLOC_USAGE_PROTECTED |
                                                       GRALLOC_USAGE_PRIVATE_CP_BUFFER | GRALLOC_USAGE_PRIVATE_UNCACHED);
                 } else {
-                        nativeBuffersUsage->nUsage = (GRALLOC_USAGE_PRIVATE_IOMMU_HEAP);
+                        nativeBuffersUsage->nUsage = (GRALLOC_USAGE_PRIVATE_IOMMU_HEAP | GRALLOC_USAGE_PRIVATE_UNCACHED);
                 }
 #else
 #if defined (MAX_RES_720P) ||  defined (MAX_RES_1080P_EBI)