hw/gpio/zaurus.c: Use LOG_GUEST_ERROR for bad guest register accesses

hw/gpio/zaurus.c: Use LOG_GUEST_ERROR for bad guest register accesses

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

Since this was the only use of the zaurus_printf() macro outside
spitz.c, we can move the definition of that macro from sharpsl.h
to spitz.c.

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: 20200628142429.17111-14-peter.maydell@linaro.org