BCM471X and BCM535X are of the same family (from what I can derive from
internal documents).  Group them into the case statement together, which
results in more code reuse.

Also, use existing helper variables to make the code a little more
readable too.
Signed-off-by: NJon Mason <jon.mason@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>