[IPX]: Correct argument type of ipxrtr_delete().

A single caller passes __u32. Inside function "net" is compared with
__u32 (__be32 really, just wasn't annotated).

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>