testing/linux-powkiddy-x55: upgrade to 6.8.6 (MR 4972)

[ci:skip-build]: already built successfully in CI

device/testing/linux-powkiddy-x55/APKBUILD

 # Maintainer: Vitaliy Ognev <vitaliy.ognev@gmail.com>
 pkgname=linux-powkiddy-x55
 pkgdesc="The $pkgname kernel and modules"
-pkgver=6.8.1
-pkgrel=2
+pkgver=6.8.6
+pkgrel=0
 arch="aarch64"
 url="https://kernel.org"
 license="GPL-2.0-only"
@@ -66,7 +66,7 @@ package() {
 }
 
 sha512sums="
-255921dd12f1043a4db38b5435b34773267c592f6712815c0851f1e0add71131fb00fd00746200eabdad29ba5b6e38a768da9c048da47fb5aa59d8eaef7d236e  linux-6.8.1.tar.xz
+5da8000a640243d06c456eb4102592134fcc5051785d91c53845fd693d0b0aca9751a7179ab8c8bdc633fc039c7ce8cfbec8357fdca9d01509b2dfb251b2586c  linux-6.8.6.tar.xz
 b38ed4cfe0f20b440426c4ba55eb727cfa64f01370f22d7aca486df4f44aceec1c1d0790c29b8984b151bee0d3ef671253d220dc0c7bec9fef6a4ce1b6cf6169  rtw88_wifi_fix.patch
 98e005a5d456a6c42dd8ae6b758737ef8a42f15edd3a418b148bfc2bace8157973dc42155c1c547dfe5ba643934bd25fd41a77bbf4838a0bbb30f7f774582b28  config-powkiddy-x55.aarch64
 "