iwlagn: do not check for AP mode for WEP keys

Even when we configure WEP keys in AP mode
ones without a station pointer are default
keys, so don't check for AP mode here.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>