qemu: discard legacy bios mailbox and support arm-tf boot scheme
qemu: discard legacy bios mailbox and support arm-tf boot scheme

Replace the unused bios_qemu_tz_arm mailbox for waking secondary boot
cores with the mailbox used by the Arm trusted firmware.

Signed-off-by: Etienne Carriere <f21bc5b8f3ea1962eb45af359f1abea6578cab94@linaro.org>
Reviewed-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>
Tested-by: Jens Wiklander <7706914404370d7502c27a0eff493dcf491feb51@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os