Limit which "pfs" when querying mellanox cards

https://docs.nvidia.com/dgx/dgx-os-7-user-guide/known_issues.html#id16

With this note:

Accessing PF0 and PF1 is restricted. Currently, there is no temporary solution available.

[11176.517416] mlx5_core 0000:05:00.0: mlx5_cmd_out_err:835:(pid 18360): ACCESS_REG(0x805) op_mod(0x1) failed, status bad operation(0x2), syndrome (0x9a6171), err(-22)
[11176.534892] mlx5_core 0000:05:00.0: mlx5_cmd_out_err:835:(pid 18360): ACCESS_REG(0x805) op_mod(0x1) failed, status bad operation(0x2), syndrome (0x9a6171), err(-22)
[11176.589308] mlx5_core 0000:05:00.1: mlx5_cmd_out_err:835:(pid 10354): ACCESS_REG(0x805) op_mod(0x1) failed, status bad operation(0x2), syndrome (0x9a6171), err(-22)
[11176.607052] mlx5_core 0000:05:00.1: mlx5_cmd_out_err:835:(pid 10354): ACCESS_REG(0x805) op_mod(0x1) failed, status bad operation(0x2), syndrome (0x9a6171), err(-22)

I didn't find a github issue about this in here. Maybe there could be a way to limit which PFs node_exporter tries to get data about?

Start by reproducing the reported ACCESS_REG errors on a system with Mellanox cards and inspect how node_exporter queries PFs. Determine where PF selection is handled and define the configuration or filtering behavior needed to skip restricted PF0 and PF1. Done means the exporter no longer triggers these errors while still collecting data from permitted PFs.