niu: Naming interrupt vectors.

 A patch to put names on the niu interrupt vectors according the syntax below.
 This is needed to assign correct affinity.

 > So on a multiqueue card with 2 RX queues and 2 TX queues we'd
 > have names like:
 >
 > 	eth0-rx-0
 > 	eth0-rx-1
 > 	eth0-tx-0
 > 	eth0-tx-1

Signed-off-by: Robert Olsson <robert.olsson@its.uu.se>
Tested-by: Jesper Dangaard Brouer <jdb@comx.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>