system-linux: refresh MAC address on DSA port conduit change

system-linux: refresh MAC address on DSA port conduit change

On changing the conduit for a DSA port, the conduit may have different
a MAC address. In the scenario where a port is part of a bridge and
is the primary port, some inconsistency may arise where the bridge have
the MAC address of the previous conduit and is never updated.
This inconsistency cause problem with packet forwarding with FDB and
other related problems.

To fix this, refresh the original MAC address after the conduit for the
DSA port is changed by polling the new MAC address for the device using
ioctl API.

Fixes: 2dc7f450f3a2 ("system-linux: add option to configure DSA conduit device")
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>