If sta_info_alloc fails after allocating the per CPU statistics,
they are not properly freed.

Fixes: c9c5962b ("mac80211: enable collecting station statistics per-CPU")
Signed-off-by: NSara Sharon <sara.sharon@intel.com>
Signed-off-by: NLuca Coelho <luciano.coelho@intel.com>
Signed-off-by: NJohannes Berg <johannes.berg@intel.com>