Merge branch 'bridge_external_fdb_aging'

Scott Feldman says:

====================
bridge: don't age out externally added FDB entries

v3: Per davem review: add del_timer_sync on rocker port remove.

v2: Per Jiri review comment: add BR_DEFAULT_AGEING_TIME to defines

Siva originally proposed skipping externally added FDB entries in the bridge's
FDB garbage collection func, and moving the ageing of externally added entries
to the port driver/device.  This broke rocker, since rocker didn't have a
hardware (or software) mechanism for ageing out its learned FDB entries.

This patchset reintroduces Siva's bridge driver patch to skip externally added
entries and adds support in rocker so rocker can age out its own entries.
Rocker does this using a software timer similar to the bridge's FDB garbage
collection timer.  Other switchdev devices/drivers can use this software timer
method or program the device to nofity aged-out entries to the driver.

Updated switchdev.txt documentation to reflect current state-of-the-art.  This
removes one more XXX todo comment in switchdev.txt.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>