BugLink: https://bugs.launchpad.net/bugs/1864773

[ Upstream commit 002dfe80 ]

The "priv->phy_mode" variable is an enum and in this context GCC will
treat it as unsigned to the error handling will never trigger.

Fixes: 57c5bc9a ("net: hisilicon: add hix5hd2 mac driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>