fix(tftf): align with RMM bet0 return code

Update test cases return codes according to
RMM Bet0 Specification. These changes are based on
https://review.trustedfirmware.org/c/TF-A/tf-a-tests/+/17892



This patch also fixes failure of
'Access from a SP to a Root region' tests when SPMC
is not present.

Signed-off-by: AlexeiFedorov <Alexei.Fedorov@arm.com>
Change-Id: I340f2b3bcee2b072f3874fd6a9f211b48ddf882b