[run] Add 11NA flags for 5G NICs that support HT.

Now that I'm a proud owner of an ASUS USB-N66, I can test 2G/5G and
3-stream configurations.

For now, just flip on 5G HT rates. I've tested this in both
5G HT20 and 5G 11a modes. It's still one stream for now until
we verify that the number of streams reported (ie the MIMO below)
is actually the number of 11n streams, NOT the number of antennas.
(They don't have to match! You can have more antennas than MIMO
streams!)

Tested:

• run0: MAC/BBP RT3593 (rev 0x0402), RF RT3053 (MIMO 3T3R)