be2net: Fix NULL pointer dereference in be_cmd_get_mac_from_list

In the Linux kernel, the following vulnerability has been resolved:

be2net: Fix NULL pointer dereference in be_cmd_get_mac_from_list

When the parameter pmac_id_valid argument of be_cmd_get_mac_from_list() is set to false, the driver may request the PMAC_ID from the firmware of the network card, and this function will store that PMAC_ID at the provided address pmac_id. This is the contract of this function.

However, there is a location within the driver where both pmac_id_valid == false and pmac_id == NULL are being passed. This could result in dereferencing a NULL pointer.

To resolve this issue, it is necessary to pass the address of a stub variable to the function.