libbinder_ndk: AParcel 'operator->' -> 'get'

Using 'operator->' directly is not very readable, and I'd rather not
have both. This is much cleaner.

Bug: 111445392
Test: ./ndk/runtests.sh
Change-Id: Ifcd828ee226225ddd298719e640f0d22bd9e5013
4 files changed