We check ether_type before registering the platform device in
arch/m68k/mac/config.c. Doing the same test again in the driver is
redundant so remove it.

Multiple probes should not happen since the conversion to platform devices,
so lose that test too.

Then macmace.c need not include macintosh.h, so remove that and irq.h and
include linux/interrupt.h explicitly.

Tested on PowerBook 520, Quadra 660av, LC 630.
Signed-off-by: NFinn Thain <fthain@telegraphics.com.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>