ffmpeg: move dav1d support patch to separate patch dir

av1 patch is now included in kodi ffmpeg fork so we can drop it
from our local patches.

Only Amlogic still needs the patch as it doesn't use kodi ffmpeg
fork.

Signed-off-by: Matthias Reichl <hias@horus.com>

packages/multimedia/ffmpeg/package.mk

@@ -14,7 +14,7 @@ case "${PROJECT}" in
     PKG_VERSION="0e5290bcac015e52f6a65dafaf41ea125816257f" # dev/4.4/rpi_import_1
     PKG_SHA256="4bd6e56920b90429bc09e43cda554f5bb9125c4ac090b4331fc459bb709eea68"
     PKG_URL="https://github.com/jc-kynesim/rpi-ffmpeg/archive/${PKG_VERSION}.tar.gz"
-    PKG_PATCH_DIRS="libreelec"
+    PKG_PATCH_DIRS="libreelec dav1d"
     ;;
   RPi)
     PKG_VERSION="4.4.1-Nexus-Alpha1"