net: mscc: ocelot: remove redundant dev_err call in vsc9959_mdio_bus_alloc()

There is a error message within devm_ioremap_resource
already, so remove the dev_err call to avoid redundant
error message.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Guobin Huang <huangguobin4@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit a180be79)
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
[Xulin: Original patch taken from
https://github.com/vladimiroltean/linux/commits/felix-dsa-tag-vlan-stable

]
Signed-off-by: Xulin Sun <xulin.sun@windriver.com>