bonding: fix panic if initialization fails

If module initialisation failed (e.g. because the bonding sysfs entry
cannot be created), kernel panics:
 IP: [<ffffffff8024910a>] destroy_workqueue+0x2d/0x146
Call Trace:
 [<ffffffff808268c4>] bond_destructor+0x28/0x78
 [<ffffffff80b64471>] netdev_run_todo+0x231/0x25a
 [<ffffffff80b6dbcd>] rtnl_unlock+0x9/0xb
 [<ffffffff81567907>] bonding_init+0x83e/0x84a

Remove the calls to bond_work_cancel_all() and destroy_workqueue();
both are also called/scheduled via bond_free_all().

bond_destroy_sysfs is unecessary because the sysfs entry has
not been created in the error case.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>