hw/arm/spitz: Use LOG_GUEST_ERROR for bad guest register accesses

hw/arm/spitz: Use LOG_GUEST_ERROR for bad guest register accesses

Instead of logging guest accesses to invalid register offsets in the
Spitz flash device with zaurus_printf() (which just prints to stderr),
use the usual qemu_log_mask(LOG_GUEST_ERROR,...).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-id: 20200628142429.17111-15-peter.maydell@linaro.org