ioctl: print unrecognized ioctl codes in _IOC(dir,type,nr,size) format

* defs.h (ioctl_print_code): New prototype.
* ioctl.c: Include xlat/ioctl_dirs.h.
(ioctl_print_code): New function.
* io.c (sys_ioctl): Use it.
* xlat/ioctl_dirs.in: New file.
diff --git a/xlat/ioctl_dirs.in b/xlat/ioctl_dirs.in
new file mode 100644
index 0000000..4c97a86
--- /dev/null
+++ b/xlat/ioctl_dirs.in
@@ -0,0 +1,3 @@
+_IOC_READ
+_IOC_WRITE
+_IOC_NONE