cfg80211: Properly track transmitting and non-transmitting BSS

When holding data of the non-transmitting BSS, we need to keep the
transmitting BSS data on. Otherwise it will be released, and release
the non-transmitting BSS with it.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>