serial: 8250_pci: Add F81504A series Support

Fintek F81504A/508A/512A is PCIE to 4/8/12 UARTs device. It's support
IO/MMIO/PCIE conf to access all functions. The old F81504/508/512 is
only support IO.

Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
Link: https://lore.kernel.org/r/1565933249-23076-1-git-send-email-hpeter+linux_kernel@gmail.com


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