composer: 2.4: vts: Add missing COMPOSER_OVERLAY allocation flag

Without this flag, the composer will fail to PRESENT the buffer on
the systems that do not have IOMMU support and can scanout contiguous-
only buffers.

Signed-off-by: Roman Stratiienko <roman.o.stratiienko@globallogic.com>
Change-Id: I566534a2a1fb602c0ce69ef861805d4fb03d7c47
diff --git a/graphics/composer/2.4/vts/functional/VtsHalGraphicsComposerV2_4TargetTest.cpp b/graphics/composer/2.4/vts/functional/VtsHalGraphicsComposerV2_4TargetTest.cpp
index b071f71..fa294ff 100644
--- a/graphics/composer/2.4/vts/functional/VtsHalGraphicsComposerV2_4TargetTest.cpp
+++ b/graphics/composer/2.4/vts/functional/VtsHalGraphicsComposerV2_4TargetTest.cpp
@@ -161,7 +161,8 @@
         return mGralloc->allocate(
                 width, height, /*layerCount*/ 1,
                 static_cast<common::V1_1::PixelFormat>(PixelFormat::RGBA_8888),
-                static_cast<uint64_t>(BufferUsage::CPU_WRITE_OFTEN | BufferUsage::CPU_READ_OFTEN));
+                static_cast<uint64_t>(BufferUsage::CPU_WRITE_OFTEN | BufferUsage::CPU_READ_OFTEN |
+                                      BufferUsage::COMPOSER_OVERLAY));
     }
 
     struct TestParameters {