net: ni65: Avoid typecast of pointer to u32

Building alpha:allmodconfig results in the following error.

drivers/net/ethernet/amd/ni65.c: In function 'ni65_stop_start':
drivers/net/ethernet/amd/ni65.c:751:37: error:
	cast from pointer to integer of different size
		buffer[i] = (u32) isa_bus_to_virt(tmdp->u.buffer);

'buffer[]' is declared as unsigned long, so replace the typecast to u32
with a typecast to unsigned long to fix the problem.

Cc: Arnd Bergmann <arnd@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>