serial: 8250: Dissociate 4MHz Titan ports from Oxford ports

[ Upstream commit f771a34b

 ]

Oxford Semiconductor PCIe (Tornado) serial port devices have their baud
base set incorrectly, however their `pciserial_board' entries have been
reused for Titan serial port devices.  Define own entries for the latter
devices then, carrying over the settings, so that Oxford entries can be
fixed.

Signed-off-by: Maciej W. Rozycki <macro@orcam.me.uk>
Link: https://lore.kernel.org/r/alpine.DEB.2.21.2106100142310.5469@angie.orcam.me.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>