mm/secretmem: make use of folio_{zap,restore}_direct_map

On Sun, Jul 26, 2026 at 10:22:35PM +0000, Brendan Jackman wrote: > From: Nikita Kalyazin nikita.kalyazin@linux.dev > > Replace set_direct_map_*_noflush with newly available > folio_zap_direct_map c