Add upstream option: --enable-rkmpp

RockChip Media Process Platform (MPP).

References
----------
http://git.videolan.org/?p=ffmpeg.git;a=commit;h=f3aefb3e1c3c6afeaca889d4fd2648458fd74dfe

.SRCINFO

@@ -1,9 +1,9 @@
 # Generated by mksrcinfo v8
-# Sun Oct 15 19:28:53 UTC 2017
+# Tue Oct 24 19:25:39 UTC 2017
 pkgbase = ffmpeg-full
 	pkgdesc = Record, convert and stream audio and video (all possible features including nvenc, qsv and libfdk-aac)
 	pkgver = 3.4
-	pkgrel = 1
+	pkgrel = 2
 	url = http://www.ffmpeg.org/
 	arch = i686
 	arch = x86_64
@@ -93,6 +93,7 @@ pkgbase = ffmpeg-full
 	depends = vo-amrwbenc
 	depends = xavs
 	depends = libmysofa
+	depends = rockchip-mpp
 	provides = ffmpeg
 	provides = ffmpeg-full-nvenc
 	provides = ffmpeg-nvenc