bonding: fix bond_open() don't always set slave active flag

Mode 802.3ad, fix incorrect bond slave active state when slave is not in
active aggregator. During bond_open(), the bonding driver always sets
the slave active flag to true if the bond is not in active-backup, alb,
or tlb modes. Bonding should let the aggregator selection logic set the
active flag when in 802.3ad mode.

Cc: Andy Gospodarek <gospo@cumulusnetworks.com>
Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: Wilson Kok <wkok@cumulusnetworks.com>
Signed-off-by: Jonathan Toppins <jtoppins@cumulusnetworks.com>
Signed-off-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>