Cleanup way elidable types are determined.

After adding the pointer type, it didn't make sense for elidable types
to be specified in canElideCallback. Now the decision as to whether a
specific type is elidable has been moved into 'isElidableType' on the
Type class.

Bug: 33298401
Test: mma in hardware/interfaces
Change-Id: I66cbaed4c533013a52e59fc8e7edcdabc9ab9f20
diff --git a/Type.cpp b/Type.cpp
index c5e55a9..107e502 100644
--- a/Type.cpp
+++ b/Type.cpp
@@ -116,6 +116,10 @@
     return scalarType->isValidEnumStorageType();
 }
 
+bool Type::isElidableType() const {
+    return false;
+}
+
 std::string Type::getCppType(StorageMode, bool) const {
     CHECK(!"Should not be here");
     return std::string();