Revert "net/mlx5: Expose vnic diagnostic counters for eswitch managed vports"

This reverts commit 606e6a72

1 which exposes
the vnic diagnostic counters via debugfs. Instead, The upcoming series will
expose the same counters through devlink health reporter.

Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>