devlink: Improve the port attributes description

devlink: Improve the port attributes description

Current PF number description is vague, sometimes interpreted as
some PF index. VF number in the PCI specification starts at 1; however
in kernel, it starts at 0 for representor model.

Improve the description of devlink port attributes PF, VF and SF
numbers with these details.

Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Reviewed-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Parav Pandit <parav@nvidia.com>
Link: https://patch.msgid.link/20241224183706.26571-1-parav@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>