kernel: Fix of 8 CVEs

rtmutex: Use waiter::task instead of current in removewaiter CVE-2026-43499 - xfs: fix freemap adjustments when adding xattrs to leaf blocks CVE-2026-43158 - xfs: delete attr leaf freemap entries when empty CVE-2026-43158 - ALSA: 6fire: fix use-after-free on disconnect CVE-2026-31581 - brcmfmac:...