test(realm): add test for FEAT_DIT

Add testcase to enable FEAT_DIT in realm.
Test if DIT Bit is preserved across context switch RL/NS.

Change-Id: I26cbaaf669b53ecba14a451955b6f847c45e0575
Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
4 files changed