net/mlx4_core: Fix sl_to_vl_change bit offset in flags2 dump

The index value in function dump_dev_cap_flags2() for outputting
"sl to vl mapping table change event support" needs to be
consistent with the value of the enumerated constant
MLX4_DEV_CAP_FLAG2_SL_TO_VL_CHANGE_EVENT defined in file
include/linux/mlx4_device.h

The change here restores that consistency.

Fixes: fd10ed8e ("IB/mlx4: Fix possible vl/sl field mismatch in LRH header in QP1 packets")
Reported-by: Mukesh Kacker <mukesh.kacker@oracle.com>
Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>