net: dsa: Fix an error handling path in 'dsa_switch_parse_ports_of()'

net: dsa: Fix an error handling path in 'dsa_switch_parse_ports_of()'

If we return before the end of the 'for_each_child_of_node()' iterator, the
reference taken on 'port' must be released.

Add the missing 'of_node_put()' calls.

Fixes: da65645b5ea7 ("net: dsa: Add new binding implementation")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/15d5310d1d55ad51c1af80775865306d92432e03.1634587046.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Jakub Kicinski <kuba@kernel.org>