Merge changes from topic "ns/spmc_at_el3" into integration
* changes:
feat(rdn2): introduce platform handler for Group0 interrupt
feat(rdn2): add plat hook for memory transaction
feat(rdn2): introduce accessor function to obtain datastore
feat(spm): separate StMM SP specifics to add support for a S-EL0 SP
feat(rdn2): add defines needed for spmc-el3
feat(ras): reuse SPM_MM specific defines for SPMC_AT_EL3
feat(bl31): reuse SPM_MM specific defines for SPMC_AT_EL3
feat(arm): reuse SPM_MM specific defines for SPMC_AT_EL3
feat(el3-spmc): add a flag to enable support to load SEL0 SP
refactor(spm-mm): reorganize secure partition manager shim code