Core: Refine psa_connect return code

According to PSA FF, psa_connect() should return
'PSA_CONNECTION_BUSY' to the caller when SPM cannot make
the connection at the moment.

Change-Id: Ibc487ea3766c31df69aad3227b665de0568867a9
Signed-off-by: Summer Qin <summer.qin@arm.com>
1 file changed