bnx2x: Fix build with SRIOV disabled.

drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c: In function 'bnx2x_drv_info_ether_stat':
drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c:3302:46: error: dereferencing pointer to incomplete type
make[6]: *** [drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.o] Error 1

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>