serial: 8250_pci: Add support for Sunix serial boards

Add support to Sunix serial boards with up to 16 ports.

Sunix board need its own setup callback instead of using Timedia's, to
properly support more than 4 ports.

Cc: Morris Ku <morris_ku@sunix.com>
Cc: Debbie Liu <debbie_liu@sunix.com>
Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
Link: https://lore.kernel.org/r/20190809190130.30773-1-kai.heng.feng@canonical.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>