When the bonding module is loaded, it creates bond0 by default.
Then, when attempting to create bond0, the following messages
are printed to syslog:

    kernel: bonding: bond0 is being created...
    kernel: bonding: Bond creation failed.

Which seems to indicate a problem, when in reality there is no
problem.  Since the actual error code is passed down from bond_create,
make use of it to print a bit less ominous message:

    kernel: bonding: bond0 is being created...
    kernel: bond0 already exists.
Signed-off-by: Phil Oester <kernel@linuxace.com>
Signed-off-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: David S. Miller <davem@davemloft.net>