linux-fairphone-fp3: drop (MR 6245)

The kernel doesn't compile anymore due to updated toolchain:

  scripts/Makefile.lib:414: *** prerequisites cannot be defined in recipes.  Stop.
  make[3]: *** [../scripts/Makefile.modbuiltin:54: techpack/audio/dsp] Error 2

Remove it since mainline kernel is working better anyways.

device/testing/linux-fairphone-fp3/APKBUILD

@@ -1,73 +0,0 @@
-# Reference: <https://postmarketos.org/vendorkernel>
-# Kernel config based on: arch/arm64/configs/lineageos_FP3_defconfig
-
-pkgname=linux-fairphone-fp3
-pkgver=4.9.218
-pkgrel=1
-pkgdesc="Fairphone 3 kernel fork"
-arch="aarch64"
-_carch="arm64"
-_flavor="fairphone-fp3"
-url="https://kernel.org"
-license="GPL-2.0-only"
-options="!strip !check !tracedeps pmb:cross-native"
-makedepends="
-	bash
-	bc
-	bison
-	devicepkg-dev
-	flex
-	openssl-dev
-	perl
-	dtc
-	dtbtool
-	gcc6
-"
-
-# building with newer gcc causes build errors
-if [ "${CC:0:5}" != "gcc6-" ]; then
-	CC="gcc6-$CC"
-	HOSTCC="gcc6-gcc"
-	CROSS_COMPILE="gcc6-$CROSS_COMPILE"
-fi
-
-# Source
-_repository="android_kernel_fairphone_FP3"
-_commit="cb219d777064c83121fbaf2aa119f842c258b3b2"
-_config="config-$_flavor.$arch"
-source="
-	$pkgname-$_commit.tar.gz::https://gitlab.e.foundation/e/devices/$_repository/-/archive/$_commit/$_repository-$_commit.tar.gz
-	$_config
-"
-builddir="$srcdir/$_repository-$_commit"
-_outdir="out"
-
-prepare() {
-	default_prepare
-	REPLACE_GCCH=0 . downstreamkernel_prepare
-}
-
-build() {
-	unset LDFLAGS
-	make O="$_outdir" ARCH="$_carch" CC="${CC:-gcc}" DTC=dtc \
-		KBUILD_BUILD_VERSION="$((pkgrel + 1 ))-postmarketOS"
-
-	dtbTool -p scripts/dtc/ -o "$_outdir/arch/$_carch/boot/dt.img" \
-		"$_outdir/arch/$_carch/boot/"
-}
-
-package() {
-	downstreamkernel_package "$builddir" "$pkgdir" "$_carch" "$_flavor" "$_outdir"
-
-	unset LDFLAGS
-	make O="$_outdir" ARCH="$_carch" CC="${CC:-gcc}" \
-		KBUILD_BUILD_VERSION="$((pkgrel + 1 ))-postmarketOS" \
-		INSTALL_MOD_PATH="$pkgdir" INSTALL_MOD_STRIP=1 modules_install
-
-	install -Dm644 "$_outdir/arch/$_carch/boot/dt.img" "$pkgdir/boot/dt.img"
-}
-
-sha512sums="
-c56a5f57155e5f68770e85d50530ff87d09c545fb8c774faae61ee4ea8147842430dab9fa20b277388ddae87e5dd6a4f6393cce2bb5fc80cfdd50514fc11c281  linux-fairphone-fp3-cb219d777064c83121fbaf2aa119f842c258b3b2.tar.gz
-23c69ac1aa04152ae7033506956bf4c64a521e8dff71e47241e27809ead80e33c522aa70a088b3c9cf390b2fa6dba858c81738958efc217dddc023412fe20167  config-fairphone-fp3.aarch64
-"