bonding: don't call update_speed_duplex() under spinlocks

bond_update_speed_duplex() might sleep while calling underlying slave's
routines. Move it out of atomic context in bond_enslave() and remove it
from bond_miimon_commit() - it was introduced by commit 546add79, however
when the slave interfaces go up/change state it's their responsibility to
fire NETDEV_UP/NETDEV_CHANGE events so that bonding can properly update
their speed.

I've tested it on all combinations of ifup/ifdown, autoneg/speed/duplex
changes, remote-controlled and local, on (not) MII-based cards. All changes
are visible.

Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>