AArch64: Make frameworks/base code more portable

Changes in this patch include

[x] Use %zu for size_t, %zd for ssize_t

[x] Some minor changes have been done to conform with
    standard JNI practice (e.g. use of jint instead of int
    in JNI function prototypes)

Change-Id: Id1aaa7894a7d0b85ac7ecd7b2bfd8cc40374261f
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>
Signed-off-by: Craig Barber <craig.barber@arm.com>
Signed-off-by: Kévin PETIT <kevin.petit@arm.com>
Signed-off-by: Marcus Oakland <marcus.oakland@arm.com>