drivers/net: fix build warnings with CONFIG_PM_SLEEP disabled

This fixes a couple of build warnings when CONFIG_PM is enabled but
CONFIG_PM_SLEEP is disabled. Applies on top of v2.6.38-rc7 - I know it's
late, but it would be great if v2.6.38 could compile without warnings!

Signed-off-by: Michel Lespinasse <walken@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>