Currently when netdev fails to allocate the error return path
fails to free the allocated object 'lid'.  Fix this by setting
err to the return error code and jumping to a new label that
performs the kfree of lid before returning.

Addresses-Coverity: ("Resource leak")
Fixes: 4b03b273 ("ionic: get MTU from lif identity")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>