Merge changes from topic "spmd-sel2" into integration

* changes:
  SPMD: add command line parameter to run SPM at S-EL2 or S-EL1
  SPMD: smc handler qualify secure origin using booleans
  SPMD: SPMC init, SMC handler cosmetic changes
  SPMD: [tegra] rename el1_sys_regs structure to sys_regs
  SPMD: Adds partially supported EL2 registers.
  SPMD: save/restore EL2 system registers.