Revert "net: rtnetlink: Enslave device before bringing it up"

This reverts commit a4abfa62.

The patch broke:
> ip link set dummy0 up
> ip link set dummy0 master bond0 down

This last command is useful to be able to enslave an interface with only
one netlink message.

After discussion, there is no good reason to support:
> ip link set dummy0 down
> ip link set dummy0 master bond0 up
because the bond interface already set the slave up when it is up.

Cc: stable@vger.kernel.org
Fixes: a4abfa62 ("net: rtnetlink: Enslave device before bringing it up")
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Hangbin Liu <liuhangbin@gmail.com>
Link: https://lore.kernel.org/r/20240108094103.2001224-2-nicolas.dichtel@6wind.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>