Adding Testing Realm Payload. This is the realm
dummy payload that is loaded as default if the RMM
is not loaded into BL32.  There are basic SMC
calls supported which include version request and
granule transition that is exercised from TFTF.
This is communicated to RMMD via SMC calls
from non secure world.
Signed-off-by: John Powell <john.powell@arm.com>
Change-Id: I489cb145866f05bb30dd4802a98464024af02fbf