layers: Simplified CastFromHandle argument deduction

By putting the return value as the first template arguement, only the
first argument is needed typically (the second can be deduced).

Change-Id: I4d0900bc03980f856c0c3bec87ab7eb1bd98aa44
diff --git a/layers/vk_layer_utils.h b/layers/vk_layer_utils.h
index e59d7bc..bf28fce 100644
--- a/layers/vk_layer_utils.h
+++ b/layers/vk_layer_utils.h
@@ -167,7 +167,7 @@
     static_assert(sizeof(HandleType) >= sizeof(ValueType), "HandleType must large enough to hold internal value");
     *handle = CastFromUint64<HandleType>(CastToUint64<ValueType>(value));
 }
-// This form is conveniently "inline" but inconveniently requires both template arguments.
+// This form is conveniently "inline", you should only need to specify the handle type (the value type being deducible from the arg
 template <typename HandleType, typename ValueType>
 HandleType CastToHandle(ValueType value) {
     HandleType handle;
@@ -175,12 +175,12 @@
     return handle;
 }
 
-template <typename HandleType, typename ValueType>
+template <typename ValueType, typename HandleType>
 void CastFromHandle(HandleType handle, ValueType *value) {
     static_assert(sizeof(HandleType) >= sizeof(ValueType), "HandleType must large enough to hold internal value");
     *value = CastFromUint64<ValueType>(CastToUint64<HandleType>(handle));
 }
-template <typename HandleType, typename ValueType>
+template <typename ValueType, typename HandleType>
 ValueType CastFromHandle(HandleType handle) {
     ValueType value;
     CastFromHandle(handle, &value);