Audio VTS: Allow 4GB buffer prepareToWrite/Read to succeed on 64 bits am: ce607879ba am: 5b122a7408  -s ours am: 0b9f25d5c9  -s ours
am: 74878cbab2  -s ours

Change-Id: Ia64cef80970727b6011a13cb3367640936938d99