Adjust the channel to correctly setup the HT flags when transitioning
an IBSS VAP to RUN.
An 11n IBSS was beaconing HTINFO/HTCAP IE's that didn't have any HT
information setup (like the HT TX/RX MCS bitmask.)
Tested:
- AR9280, IBSS - both a statically setup channel and a scanned channel
PR: kern/172955