layers: Consolidate GetPhysicalDevice* accessors

Simplified core_validation->descriptor_sets/buffer_validation.

Change-Id: I6921ac458bce5899e8bd60145bfaa0e0f5e8a2ac
diff --git a/layers/descriptor_sets.cpp b/layers/descriptor_sets.cpp
index 44769ce..ad3d720 100644
--- a/layers/descriptor_sets.cpp
+++ b/layers/descriptor_sets.cpp
@@ -309,7 +309,7 @@
       pool_state_(nullptr),
       p_layout_(layout),
       device_data_(dev_data),
-      limits_(GetPhysicalDeviceLimits(dev_data)) {
+      limits_(GetPhysDevProperties(dev_data)->properties.limits) {
     pool_state_ = GetDescriptorPoolState(dev_data, pool);
     // Foreach binding, create default descriptors of given type
     for (uint32_t i = 0; i < p_layout_->GetBindingCount(); ++i) {