tg3: Expand 5719 workaround

As a precautionary measure, expand the fix submitted in commit
4d163b75 entitled "tg3: Fix 5719 A0 tx
completion bug" to apply to all 5719 revisions.

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