hw/arm: highbank: For EL3 guests, don't enable PSCI, start all cores

hw/arm: highbank: For EL3 guests, don't enable PSCI, start all cores

Change the highbank/midway boards to use the new boot.c functionality
to allow us to enable psci-conduit only if the guest is being booted
in EL1 or EL2, so that if the user runs guest EL3 firmware code our
PSCI emulation doesn't get in its way.

To do this we stop setting the psci-conduit and start-powered-off
properties on the CPU objects in the board code, and instead set the
psci_conduit field in the arm_boot_info struct to tell the common
boot loader code that we'd like PSCI if the guest is starting at an
EL that it makes sense with (in which case it will set these
properties).

This means that when running guest code at EL3, all the cores
will start execution at once on poweron. This matches the
real hardware behaviour. (A brief description of the hardware
boot process is in the u-boot documentation for these boards:
https://u-boot.readthedocs.io/en/latest/board/highbank/highbank.html#boot-process
 -- in theory one might run the 'a9boot'/'a15boot' secure monitor
code in QEMU, though we probably don't emulate enough for that.)

This affects the highbank and midway boards.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Tested-by: Cédric Le Goater <clg@kaod.org>
Tested-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Message-id: 20220127154639.2090164-10-peter.maydell@linaro.org