r8169: remove unneeded rpm ops in rtl_shutdown

This patch reverts commit 2a15cd2f "r8169: runtime resume before
shutdown" from 2012. Few months after this change the underlying issue
was solved in the PCI core with commit 3ff2de9b

 "PCI/PM: Resume
device before shutdown".

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>