layers: Rename format utils, strip Vk

Change-Id: I4d192db22c51d2e9224b74487bfd5d6a58405028
diff --git a/layers/descriptor_sets.cpp b/layers/descriptor_sets.cpp
index fbaa2dc..84663c4 100644
--- a/layers/descriptor_sets.cpp
+++ b/layers/descriptor_sets.cpp
@@ -785,7 +785,7 @@
     }
     // TODO : The various image aspect and format checks here are based on general spec language in 11.5 Image Views section under
     // vkCreateImageView(). What's the best way to create unique id for these cases?
-    bool ds = VkFormatIsDepthOrStencil(format);
+    bool ds = FormatIsDepthOrStencil(format);
     switch (image_layout) {
         case VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL:
             // Only Color bit must be set