mac80211: fix a possible leak of station stats

[ Upstream commit d78d9ee9d40aca4781d2c5334972544601a4c3a2 ]

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: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>