SPM: Stateless services can be searched by sid

Stateless services need to be able to be found by SID. This is
required in 'psa_connect()' and 'psa_version()' API.
Error check order in 'psa_connect()' is also updated: If a
stateless service SID is detected, block the connection directly.

Change-Id: If5182d72986173eb33ff1af99dff79cb3661f0fe
Signed-off-by: Mingyang Sun <mingyang.sun@arm.com>