net: ethernet: bgmac-platform: fix an OF node reference leak

The OF node obtained by of_parse_phandle() is not freed. Call
of_node_put() to balance the refcount.

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

Fixes: 1676aba5 ("net: ethernet: bgmac: device tree phy enablement")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241214014912.2810315-1-joe@pf.is.s.u-tokyo.ac.jp


Signed-off-by: Paolo Abeni <pabeni@redhat.com>