smsc75xx: don't enable remote wakeup directly

As pointed out by Bjorn Mork, the generic "usb" driver sets this
for us so no need to directly set it in this driver.

Signed-off-by: Steve Glendinning <steve.glendinning@shawell.net>
Cc: Bjorn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>