And fix up the code to always allow MSI on 5714 A2.

Call tg3_find_peer() earlier because we need that information before
we can determine whether we can set TG3_FLAG_SUPPORT_MSI or not.
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>