fix(cactus_tests/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: Ia0f19785b99e4b645ffa2ca61705f2329640a130
diff --git a/spm/cactus/cactus_tests/cactus_test_ffa.c b/spm/cactus/cactus_tests/cactus_test_ffa.c
index 2dc264e..c580ee4 100644
--- a/spm/cactus/cactus_tests/cactus_test_ffa.c
+++ b/spm/cactus/cactus_tests/cactus_test_ffa.c
@@ -121,7 +121,8 @@
 		&ffa_expected_partition_info[0], 1), true);
 
 	expect(ffa_partition_info_helper(mb, null_uuid,
-		ffa_expected_partition_info, 4), true);
+		ffa_expected_partition_info,
+		ARRAY_SIZE(ffa_expected_partition_info)), true);
 
 	ffa_partition_info_wrong_test();