bonding: update port speed when getting bond speed

Andrew reported a bonding issue that if we put an active-back bond on top
of a 802.3ad bond interface. When the 802.3ad bond's speed/duplex changed
dynamically. The upper bonding interface's speed/duplex can't be changed at
the same time, which will show incorrect speed.

Fix it by updating the port speed when calling ethtool.

Reported-by: Andrew Schorr <ajschorr@alumni.princeton.edu>
Closes: https://lore.kernel.org/netdev/ZEt3hvyREPVdbesO@Laptop-X1/


Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Acked-by: Jay Vosburgh <jay.vosburgh@canonical.com>
Link: https://lore.kernel.org/r/20230821101008.797482-1-liuhangbin@gmail.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>