Merge changes from topic "msm8916-spmin" into integration

* changes:
  docs(msm8916): document new build options
  feat(msm8916): allow selecting which UART to use
  feat(msm8916): add SP_MIN port for AArch32
  refactor(msm8916): detect cold boot in plat_get_my_entrypoint
  feat(msm8916): add Test Secure Payload (TSP) port
  build(msm8916): place bl32 directly after bl31
  refactor(msm8916): separate common platform setup code