Parcel.java: Fix bug where non-nested creators threw NullPointer

Upon deserialization, various APIs would check that the passed in class
was assignable from the creator's enclosing class - which was assumed to
always be the Parcelable type.

This assumption is not always true, so updating the check to explicitely
store the parcelable type

Fix: 232589966
Test: m && atest ParcelTest && atest BundleTest
Change-Id: I59b650a854944e9020615a65798c5e54f5540aaa