Documentation: Move Oxford Semiconductor PCIe (Tornado) 950 to misc-devices

Documentation/tty has been moved to driver-api, which is not suitable
for user documentation, so move the Oxford Semiconductor PCIe (Tornado)
950 description to misc-devices instead.
Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2205131823430.10656@angie.orcam.me.ukSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>