For now, just default to presenting "found" channels as 11g, not 11b.

The intel 7260 driver under development requires this - the scans come
in as normal frames but with the frequency provided. The correct method
is to have the driver provide flags (so we can determine if it's 11b
or 11g); this will have to do in the meantime.

Without this, the channel found is 11b, and no ERP (ie "11g") bits
are negotiated with the AP.

This allows the 7260 in 2ghz mode to operate in 11bg, rather than
just 11b.

Tested:

• intel 7260 driver, 11bg channels