Don't assume that size_t is 32-bit

Crypto data was being copied to java jint array in chunks of
size_t. This will not work on LP64 as size_t will be 64-bit.
This patch changes copy to use int32_t chunks instead of size_t.

Change-Id: I75d910a1182ad2f58f432cd172127f048b4c393b
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>