tg3: adapt tg3 to use reworked PCI PM code

Adapt the tg3 driver to use the reworked PCI PM and make it use the
exported PCI PM core functions instead of accessing the PCI PM registers
directly by itself.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>