net: stmmac: restructure the error path of stmmac_probe_config_dt()

net: stmmac: restructure the error path of stmmac_probe_config_dt()

Current implementation of stmmac_probe_config_dt() does not release the
OF node reference obtained by of_parse_phandle() in some error paths.
The problem is that some error paths call stmmac_remove_config_dt() to
clean up but others use and unwind ladder.  These two types of error
handling have not kept in sync and have been a recurring source of bugs.
Re-write the error handling in stmmac_probe_config_dt() to use an unwind
ladder. Consequently, stmmac_remove_config_dt() is not needed anymore,
thus remove it.

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

Fixes: 4838a5405028 ("net: stmmac: Fix wrapper drivers not detecting PHY")
Signed-off-by: Joe Hattori <joe@pf.is.s.u-tokyo.ac.jp>
Link: https://patch.msgid.link/20241219024119.2017012-1-joe@pf.is.s.u-tokyo.ac.jp
Signed-off-by: Jakub Kicinski <kuba@kernel.org>