makedepends_x86_64: switch back vmaf-git to vmaf

At the time of ffmpeg 4.0 release, the latest version of vmaf was
1.3.1. At that time, ffmpeg 4.0 needed vmaf git master to compile.

Now vmaf 1.3.4 was released and ffmpeg builds fine with it.

.SRCINFO

@@ -1,7 +1,7 @@
 pkgbase = ffmpeg-full
 	pkgdesc = Complete solution to record, convert and stream audio and video (all possible features including nvenc, qsv and libfdk-aac)
 	pkgver = 4.0
-	pkgrel = 3
+	pkgrel = 4
 	url = http://www.ffmpeg.org/
 	arch = i686
 	arch = x86_64
@@ -126,7 +126,7 @@ pkgbase = ffmpeg-full
 	sha256sums = 04a7176400907fd7db0d69116b99de49e582a6e176b3bfb36a03e50a4cb26a36
 	depends_x86_64 = cuda
 	depends_x86_64 = intel-media-sdk
-	makedepends_x86_64 = vmaf-git
+	makedepends_x86_64 = vmaf
 
 pkgname = ffmpeg-full