Fix removal of a BSS that has not yet been fully initialized

Fix removal of a BSS that has not yet been fully initialized

If a secondary BSS is removed while it is waiting for the primary BSS to
complete channel setup (e.g., due to HT co-ex scan, ACS, or DFS), the
hostapd_data instance has not yet been initialized. Fix the BSS removal
code to take this special case into account and not try to deinitialize
the hostapd_data instance that has not yet been started.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>