net: mv643xx_eth: fix an OF node reference leak

net: mv643xx_eth: fix an OF node reference leak

Current implementation of mv643xx_eth_shared_of_add_port() calls
of_parse_phandle(), but does not release the refcount on error. Call
of_node_put() in the error path and in mv643xx_eth_shared_of_remove().

This bug was found by an experimental verification tool that I am
developing.

Fixes: 76723bca2802 ("net: mv643xx_eth: add DT parsing support")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Link: https://patch.msgid.link/20241221081448.3313163-1-joe@pf.is.s.u-tokyo.ac.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>