New rtwn(4) driver for RTL8188CE wifi cards.

New rtwn(4) driver for RTL8188CE wifi cards.

This is a PCI card from the same chip family as supported by urtwn(4) on USB.
Development started in 2013 using urtwn(4) as a starting point but was dormant
for much of the time since. I finally unslacked after uwe@ provided help with
lifting this driver on its feet. As usual we got helpful hints from Theo.

Requires firmware which will be available in ports soon.

There are rate adaptation issues that still need to be fixed, cause unknown.
In my testing the hardware rarely transmits more than 1Mbit/s.

Committing over MAC/BB RTL8188CE, RF 6052 1T1R.