[scenic] Fix for vma_allocator image test

Tiled images are larger than linear images on some platform (e.g. x86). Forcing linear layout produces consistent behavior on all platforms.

tested = escher_unittests, arm64, x86

Change-Id: I4a0ece79016beb71225ac03ab1e800f8bac435cd
diff --git a/public/lib/escher/test/gpu_allocator_unittest.cc b/public/lib/escher/test/gpu_allocator_unittest.cc
index e983612..9d91051 100644
--- a/public/lib/escher/test/gpu_allocator_unittest.cc
+++ b/public/lib/escher/test/gpu_allocator_unittest.cc
@@ -183,6 +183,7 @@
   info.width = kWidth;
   info.height = kHeight;
   info.usage = kUsage;
+  info.tiling = vk::ImageTiling::eLinear;
 
   // Allocate some images, and confirm that the allocator is tracking the bytes
   // allocated.
@@ -234,6 +235,7 @@
   small_image.width = 1;
   small_image.height = 1;
   small_image.usage = kUsage;
+  info.tiling = vk::ImageTiling::eLinear;
 
   auto image_dedicated1 = allocator->AllocateImage(nullptr, small_image, &ptr);
   EXPECT_EQ(0u, ptr->offset());