The return value from kzalloc() is not checked correctly. The
test is done against a wrong variable. This patch fix it.

Fixes: f25da51f ("ieee802154: hwsim: add replacement for fakelb")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>
Signed-off-by: David S. Miller <davem@davemloft.net>