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

This reverts commit 606e6a72 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>