Pull "generic TEE subsystem for v4.12"

Introduce generic TEE subsystem:
- the TEE subsystem itself
- an OP-TEE driver using the subsystem
- optee bindings
- optee node for hi6220-hikey.dts

* tag 'tee-drv-for-4.12' of git://git.linaro.org:/people/jens.wiklander/linux-tee:
  arm64: dt: hikey: Add optee node
  Documentation: tee subsystem and op-tee driver
  tee: add OP-TEE driver
  tee: generic TEE subsystem
  dt/bindings: add bindings for optee