layers: Make device extension enables consistent

I want to get rid of the "_enable" suffix everywhere to allow for a
second instance of the same structure to represent the /supported/ set
for better diagnostics.
diff --git a/layers/descriptor_sets.cpp b/layers/descriptor_sets.cpp
index 3f5ddb5..40c280b 100644
--- a/layers/descriptor_sets.cpp
+++ b/layers/descriptor_sets.cpp
@@ -1672,7 +1672,7 @@
                         reinterpret_cast<const uint64_t &>(p_alloc_info->pSetLayouts[i]));
         }
     }
-    if (!GetDeviceExtensions(dev_data)->khr_maintenance1_enabled) {
+    if (!GetDeviceExtensions(dev_data)->khr_maintenance1) {
         auto pool_state = GetDescriptorPoolState(dev_data, p_alloc_info->descriptorPool);
         // Track number of descriptorSets allowable in this pool
         if (pool_state->availableSets < p_alloc_info->descriptorSetCount) {