[TG3]: Workaround MSI bug on 5714/5780.

[TG3]: Workaround MSI bug on 5714/5780.

A hardware bug was revealed after a recent PCI MSI patch was made to
always disable legacy INTX when enabling MSI.  The 5714/5780 chips
will not generate MSI when INTX is disabled, causing MSI failure
messages to be reported, and another patch was made to workaround the
problem by disabling MSI on ServerWorks HT1000 bridge chips commonly
found with the 5714.

We workaround this chip bug by enabling INTX after we enable MSI and
after we resume from suspend.

Update version to 3.81.

This problem was discovered by David Miller.

Signed-off-by: Michael Chan <mchan@broadcom.com>
Acked-by: Andy Gospodarek <andy@greyhouse.net>
Signed-off-by: David S. Miller <davem@davemloft.net>