net: mana: Use pci_name() for debugfs directory naming

In the Linux kernel, the following vulnerability has been resolved: net: mana: Use pci_name() for debugfs directory naming Use pci_name(pdev) for the per-device debugfs directory instead of hardcoded "0" for PFs and pci_slot_name(pdev->slot) for VFs. The previous approach had two issues: 1. pci_slot_name() dereferences pdev->slot, which can be NULL for VFs in environments like generic VFIO passthrough or nested KVM, causing a NULL pointer dereference. 2. Multiple PFs would all use "0", and VFs across different PCI domains or buses could share the same slot name, leading to -EEXIST errors from debugfs_create_dir(). pci_name(pdev) returns the unique BDF address, is always valid, and is unique across the system.