target/sh4: log unauthorized accesses using qemu_log_mask

qemu_log_mask() is preferred over fprintf() for logging errors.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
