sungem: Fix WakeOnLan

WakeOnLan was broken in this driver because gp->asleep_wol is a 1-bit
bitfield and it was being assigned WAKE_MAGIC, which is (1 << 5).
gp->asleep_wol remains 0 and the machine never wakes up.  Fixed by casting
gp->wake_on_lan to bool.  Tested on an iBook G4.

Signed-off-by: Gerard Lledo <gerard.lledo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>