net: mv643xx_eth: fix build error

Fix below build error:
  CC      drivers/net/ethernet/marvell/mv643xx_eth.o
drivers/net/ethernet/marvell/mv643xx_eth.c: In function 'mv643xx_eth_get_drvinfo':
drivers/net/ethernet/marvell/mv643xx_eth.c:1505: error: 'info' undeclared (first use in this function)
drivers/net/ethernet/marvell/mv643xx_eth.c:1505: error: (Each undeclared identifier is reported only once
drivers/net/ethernet/marvell/mv643xx_eth.c:1505: error: for each function it appears in.)
make[4]: *** [drivers/net/ethernet/marvell/mv643xx_eth.o] Error 1

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>