fix(runtime_services/ffa): dynamically calculate array size

This patch uses the ARRAY_SIZE() macro to calculate the number of
elements in the 'ffa_expected_partition_info' array instead of
hard-coding to '4'.

Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>
Change-Id: Iaa2d833a937d0d7f39a04c98a34e65f0dffe59d9
1 file changed