When mvm is initialized we alloc aux station with aux queue.
We later free the station memory when driver is stopped, but we
never free the queue's memory, which casues a leak.

Add a proper de-initialization of the station.
Signed-off-by: Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20200529092401.0121c5be55e9.Id7516fbb3482131d0c9dfb51ff20b226617ddb49@changeid