hw/arm/highbank: Use AddressSpace when using write_secondary_boot()

hw/arm/highbank: Use AddressSpace when using write_secondary_boot()

write_secondary_boot() is used in SMP configurations where the
CPU address space might not be the main System Bus.
The rom_add_blob_fixed_as() function allow us to specify an
address space. Use it to write each boot blob in the corresponding
CPU address space.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20191019234715.25750-15-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>