serial/8250_fintek: Support for any io address.

Fintek chip can be configured for io addresses different than the standard.

Query the chip for the configured addresses and try to match it with the
pnp address.

Reported-by: Peter Hong <peter_hong@fintek.com.tw>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>