Initial support for HOSTAP mode. With this bwfm(4) can spawn an access

Initial support for HOSTAP mode.  With this bwfm(4) can spawn an access
point including WPA2 support.  We now have a different event mask per
mode, so that events that are only useful for STA mode don't interfere
with HOSTAP mode.  Power savings is disabled when we act as AP. The
connection events generate 802.11 frames for handling auth/assoc and
deauth/deassoc so that our stack takes note of the connecting nodes.