CVE-2026-80867

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

alpha/PCI: Add security_locked_down() check to pci_mmap_resource()

Currently, Alpha's pci_mmap_resource() does not check
security_locked_down(LOCKDOWN_PCI_ACCESS) before allowing userspace to mmap
PCI BARs.

The generic version has had this check since commit eb627e17727e ("PCI:
Lock down BAR access when the kernel is locked down") to prevent DMA
attacks when the kernel is locked down.

Add the same check to Alpha's pci_mmap_resource().