From: Florian Fainelli
Date: Tue, 7 Feb 2017 23:10:13 -0800
> dsa_slave_create() can fail, and dsa_user_port_unapply() will properly check
> for the network device not being NULL before attempting to destroy it. We were
> not setting the slave network device as NULL if dsa_slave_create() failed,
dsa_slave_create() can fail, and dsa_user_port_unapply() will properly check
for the network device not being NULL before attempting to destroy it. We were
not setting the slave network device as NULL if dsa_slave_create() failed, so
we would later on be calling dsa_slave_destroy() on a now free'd
