r8169: fix handling ether_clk

Petr reported that system freezes on r8169 driver load on a system
using ether_clk. The original change was done under the assumption
that the clock isn't needed for basic operations like chip register
access. But obviously that was wrong.
Therefore effectively revert the original change, and in addition
leave the clock active when suspending and WoL is enabled. Chip may
not be able to process incoming packets otherwise.

Fixes: 9f0b54cd ("r8169: move switching optional clock on/off to pll power functions")
Reported-by: Petr Tesarik <ptesarik@suse.cz>
Tested-by: Petr Tesarik <ptesarik@suse.cz>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>