android: Make clang happy with braces

Fixes error:
suggest braces around initialization of subobject [-Werror,-Wmissing-braces]

Change-Id: Id090c82ebfb2b9a72e84967b98516bbf43cc6513
diff --git a/layers/descriptor_sets.cpp b/layers/descriptor_sets.cpp
index 67b0b1b..9cb7df2 100644
--- a/layers/descriptor_sets.cpp
+++ b/layers/descriptor_sets.cpp
@@ -1507,7 +1507,7 @@
     if ((type == VK_DESCRIPTOR_TYPE_SAMPLED_IMAGE) || (type == VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER)) {
         // Test that the layout is compatible with the descriptorType for the two sampled image types
         const static std::array<VkImageLayout, 3> valid_layouts = {
-            VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_GENERAL};
+            {VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL, VK_IMAGE_LAYOUT_GENERAL}};
 
         struct ExtensionLayout {
             VkImageLayout layout;