Add power_envelope & soc_power sensors

[trindenau]

    Add `power_envelope` & `soc_power` sensors

    Add `power_envelope` and `soc_power` sensors.
    Both will derive their values from `dbugfs`.
    testd by: ipmitool -I ipmb sensors:
        soc_power        | 22.000     | Watts      | ok    | na        | 5.000     | na        | na        | na        | na
        power_envelope   | 65.000     | Watts      | ok    | na        | na        | 10.000    | 150.000   | na        |na
 The change also tests whether the system is running a locked-down version of Linux. If it is not, the mlxbf_pt module will be loaded.
 Fixes jira https://redmine.mellanox.com/issues/4016386.