Vts: Add missing usage to buffer

The test's buffer is read by the GPU and therefore needs to be allocatted with
BufferUsage::GPU_TEXTURE

Fixes: 182935868
Change-Id: I7795e6a32acdf3ecf76003bd12715fcaf73a4e71
Test: VtsHalGraphicsComposerV2_2TargetTest
1 file changed