mlxbf_gige: stop PHY during open() error paths

The mlxbf_gige_open() routine starts the PHY as part of normal
initialization.  The mlxbf_gige_open() routine must stop the
PHY during its error paths.

Fixes: f92e1869

 ("Add Mellanox BlueField Gigabit Ethernet driver")
Signed-off-by: David Thompson <davthompson@nvidia.com>
Reviewed-by: Asmaa Mnebhi <asmaa@nvidia.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>