x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()

...

CVE-2025-39845

In the Linux kernel, the following vulnerability has been resolved: x86/mm/64: define ARCHPAGETABLESYNCMASK and archsynckernelmappings Define ARCHPAGETABLESYNCMASK and archsynckernelmappings to ensure page tables are properly synchronized when calling pdpopulatekernel. For 5-level paging,...