r8169: remove redundant driver message when entering promiscuous mode

Net core -  __dev_set_promiscuity - prints a message already when
promiscuous mode in entered/left, therefore we don't have to do this
in the driver too. Also the driver message would be misleading
(would be because "link" message level is disabled per default)
because it would print "promisc mode enabled" even if it's being
left. Reason is that __dev_change_flags() calls dev_set_rx_mode()
before touching the promisc flag.

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