net/mlx5: always use representor ifindex for ioctl

net/mlx5: always use representor ifindex for ioctl

In the current code, on some cases the representor ethdev is using the
PF interface to query some link status information or pause parameters.

It was done because in previous kernel versions there was no support
from the kernel for the representor info.

Using the PF i/f for such ioctl is error prone and not always working
because:
 * On some cases there is no PF at all, only representors (e.g Bluefield
   with host representors)
 * Query the up/down status from representor and link status from PF
   is in-consist
 * PF link is down doesn't necessarily means representor is down.
 * setting different pause configuration for the PF and the
   representors will result on undefined behaviour

Making the code cleaner and more robust by using only the representor
i/f for the ioctl. whatever the kernel will provide on this query will
be used. No need to do W.A. for kernel missing functionality.

Note:
 1. Setting pause parameters will obviously won't work on representors
 2. Old kernel will not report all the possible representor info

Fixes: 2b7302638898 ("net/mlx5: probe all port representors")
Cc: stable@dpdk.org
Signed-off-by: Shahaf Shuler <shahafs@mellanox.com>