net: dsa: fix phylink_start()/phylink_stop() calls

net: dsa: fix phylink_start()/phylink_stop() calls

[ Upstream commit 8640f8dc6d657ebfb4e67c202ad32c5457858a13 ]

Place phylink_start()/phylink_stop() inside dsa_port_enable() and
dsa_port_disable(), which ensures that we call phylink_stop() before
tearing down phylink - which is a documented requirement.  Failure
to do so can cause use-after-free bugs.

Fixes: 0e27921816ad ("net: dsa: Use PHYLINK for the CPU/DSA ports")
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>