layers: Verify memory is bound to images used to update descriptors

Fixes #663

For vkUpdateDescriptorSets() calls that include an image, verify that memory is bound to the image.
diff --git a/layers/descriptor_sets.cpp b/layers/descriptor_sets.cpp
index f02da6b..e017f0e 100644
--- a/layers/descriptor_sets.cpp
+++ b/layers/descriptor_sets.cpp
@@ -689,6 +689,9 @@
     if (image_node) {
         format = image_node->createInfo.format;
         usage = image_node->createInfo.usage;
+        // Validate that memory is bound to image
+        if (ValidateMemoryIsBoundToImage(dev_data, image_node, "vkUpdateDescriptorSets()"))
+            return false;
     } else {
         // Also need to check the swapchains.
         auto swapchain = getSwapchainFromImage(dev_data, image);