Add PF_IEEE80211 definition.

Reviewed by:	rpaulo
Fix a typo: s/KLSI/CATC/
Return HAL_ANT_VARIABLE for now, until it's unstubbed.

This is needed by the slow antenna diversity logic for the AR9485/AR9462
as it's only engaged if the TX diveristy is set to VARIABLE.
Set the FreeBSD capability bit to indicate that LNA diversity is enabled.

This is true for the AR9485 and AR933x SoC.