ieee802154: fix error return code in ieee802154_llsec_getparams()

Fix to return negative error code -ENOBUFS from the error handling
case instead of 0, as done elsewhere in this function.

Fixes: 3e9c156e

 ("ieee802154: add netlink interfaces for llsec")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Link: https://lore.kernel.org/r/20210519141614.3040055-1-weiyongjun1@huawei.com


Signed-off-by: Stefan Schmidt <stefan@datenfreihafen.org>