pp_test: Add isolation level 1 and IPC model config

The default SPM backend model on isolation level 1 is SFN, thus
cross call is not covered under pp_test.

Signed-off-by: Jianliang Shen <jianliang.shen@arm.com>
Change-Id: Ie6d620b0979682e690cc474eb112ffda5d897852
1 file changed