net/mlx5: HWS, fix definer's HWS_SET32 macro for negative offset

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5: HWS, fix definer's HWS_SET32 macro for negative offset

When bit offset for HWS_SET32 macro is negative,

UBSAN complains about the shift-out-of-bounds:

UBSAN: shift-out-of-bounds in

drivers/net/ethernet/mellanox/mlx5/core/steering/hws/definer.c:177:2

shift exponent -8 is negative