VMCI: fix reference to ioctl-number.rst

VMCI: fix reference to ioctl-number.rst

There has never been an ioctl-number.h — this must have been a typo
for ioctl-number.txt (which later become ioctl-number.rst).

At the time this comment was written, the note didn't actually end up
appearing anywhere, but I fixed the omission from ioctl-number.rst in
0a8e4dc1d353 ("Documentation: ioctl: document 0x07 ioctl code").

Fixes: 20259849bb1a ("VMCI: Some header and config files.")
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Link: https://lore.kernel.org/r/re3xng4uwull2cu53xnu5dtv3wlstfiv3v7rmbwtw2qbvj5mo3@q45iujse5ovc
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>