firewire: nosy: note ioctls in ioctl-number.txt

These are the ioctls for the special-purpose misc device /dev/nosy, the
interface to the IEEE 1394 packet sniffer/ protocol analyzer driver.
Currently only the numbers 00...02 are in use; let's block a few more
for unforeseen use cases.

Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>