Crypto: Cleanup usage test_aes_mode_array

Make it explicit that the NR_TEST_AES_MODE is accessing that
array to check which modes are available for testing.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: I19646e835d4354dee79fa8b690aa8dfa19156778
1 file changed