ks8842: Fix warnings on 64-bit.

drivers/net/ks8842.c:922:26: warning: cast from pointer to integer of different size
drivers/net/ks8842.c:940:17: warning: cast to pointer from integer of different size
drivers/net/ks8842.c:963:17: warning: cast to pointer from integer of different size

Signed-off-by: David S. Miller <davem@davemloft.net>