test(realm): add support for multiple realm

Add support for creating multiple realm payloads
* Layout change to reserve memory for two realm pools.
* Change offset of shared memory region between host and realm.
* Change API to get/set shared memory region for each realm

Change-Id: If0d7d2e2697052387c2ddcc729ec3872fd5dd409
Signed-off-by: Shruti Gupta <shruti.gupta@arm.com>
13 files changed