MFC: r293642

MFC: r293642

- Add support for Advantech PCI-1602 Rev. B1 and PCI-1603 cards. [1]
- Add a description of Advantech PCI-1602 Rev. A boards. [1]
- Properly set up REG_ACR also for PCI-1602 Rev. A based on what the
  Advantech-supplied Linux driver does.
- Additionally use the macros of <dev/ic/ns16550.h> to replace existing
  magic values and get rid of trivial comments.
- Fix the style of some comments.

PR:		205359 [1]
Submitted by:	Jan Mikkelsen (original patch) [1]

git-svn-id: svn://svn.freebsd.org/base/stable/10@318151 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f