tg3: Break out mini producer ring handling

This patch separates the code that sets up the mini producer ring from
the code that sets up the jumbo producer rings.  The 5717 asic rev
devices do not have a mini ring, but do have a jumbo frame
implementation similar to the 5704 and previous devices.

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>