Remove patches to ffmpeg wraps

Equivalent functionality (allowing dependencies to be meson subprojects
and fixing the zlib HAVE_UNISTD_H issue) was merged upstream now
(thanks kasper), so this is no longer necessary. dav1d is now
enabled using -Dffmpeg:libdav1d=enabled.

Author: arch1t3cht

subprojects/ffmpeg.wrap

@@ -3,7 +3,6 @@ directory = ffmpeg
 url = https://gitlab.freedesktop.org/gstreamer/meson-ports/ffmpeg.git
 revision = meson-6.1
 depth = 1
-diff_files = ffmpeg/0001.patch
 
 [provide]
 libavformat = libavformat_dep