tg3: Fix int selftest for recent devices.

This patch fixes interrupt selftest failures for recent devices (57765,
5717, 5718. 5719, 5720) by disabling MSI one-shot mode and applying the
status tag workaround to the selftest code.

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