Net / e100: Fix suspend of devices that cannot be power managed

If the adapter is not power-manageable using either ACPI, or the
native PCI PM interface, __e100_power_off() returns error code, which
causes every attempt to suspend to fail, although it should return 0
in such a case.  Fix this problem by ignoring the return value of
pci_set_power_state() in __e100_power_off().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: David S. Miller <davem@davemloft.net>