mac80211: fix misplaced while instead of if

mac80211: fix misplaced while instead of if

This never was intended to be a 'while' loop, it should've
just been an 'if' instead of 'while'. Fix this.

I noticed this while applying another patch from Ben that
intended to fix a busy loop at this spot.

Cc: stable@vger.kernel.org
Fixes: 80b194fc4454 ("mac80211: mark station unauthorized before key removal")
Reported-by: Ben Greear <greearb@candelatech.com>
Link: https://lore.kernel.org/r/20200803110209.253009ae41ff.I3522aad099392b31d5cf2dcca34cbac7e5832dde@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>