Make frameworks/av 64-bit compatible

Contains the necessary changes to make frameworks/av build and work
on a 64-bit machine.

Signed-off-by: Craig Barber <craig.barber@arm.com>
Signed-off-by: Kévin PETIT <kevin.petit@arm.com>
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>
Signed-off-by: Marcus Oakland <marcus.oakland@arm.com>

Change-Id: I725feaae50ed8eee25ca2c947cf15aee1f395c43