nl80211: trivial: Remove redundant loop

cfg80211_assign_cookie already checks & prevents a 0 from being
returned, so the explicit loop is unnecessary.

Signed-off-by: Denis Kenzior <denkenz@gmail.com>
Link: https://lore.kernel.org/r/20191008164350.2836-1-denkenz@gmail.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>