serial: 8250_pci: add support for MCS9865 / SYBA 6x Serial Port Card

This patch is heavily based on an earlier patch found on the linux-serial
mailing list [1], written by Darius Augulis.

The previous incarnation of this patch only supported a 2x serial port
card.  I have added support for my SYBA 6x serial port card, and tested on
x86.

[1]: http://marc.info/?l=linux-serial&m=124975806304760



Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Cc: Darius Augulis <augulis.darius@gmail.com>
Cc: Greg KH <greg@kroah.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>