net/mlx5: support list of representor PF

net/mlx5: support list of representor PF

To probe representors from different kernel bonding PFs, had to specify
2 separate devargs like this:
    -a 03:00.0,representor=pf0vf[0-3] -a 03:00.0,representor=pf1vf[0-3]

This patch supports range or list of PF section in devargs, so the
alternative short devargs of above is:
    -a 03:00.0,representor=pf[0-1]vf[0-3]

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>