This adds support for Fintek's 4, 8, and 12 port PCIE serial cards.

Thanks to Fintek for the sample devices, and the spec needed in order to
implement this.

Cc: Amanda Ying <amanda_ying@fintek.com.tw>
Cc: Felix Shih <felix_shih@fintek.com.tw>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>