net: mscc: ocelot: select NET_DEVLINK

Without this option, the driver fails to link:

ld.lld: error: undefined symbol: devlink_sb_register
>>> referenced by ocelot_devlink.c
>>>               net/ethernet/mscc/ocelot_devlink.o:(ocelot_devlink_sb_register) in archive drivers/built-in.a
>>> referenced by ocelot_devlink.c
>>>               net/ethernet/mscc/ocelot_devlink.o:(ocelot_devlink_sb_register) in archive drivers/built-in.a

Fixes: f59fd9ca ("net: mscc: ocelot: configure watermarks using devlink-sb")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20210225143910.3964364-1-arnd@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>
(cherry picked from commit 907310ce)
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>