rpidistro-ffmpeg: upgrade 4.3.4 -> 5.1.4

Reduce amount of patches applied as they
are no longer required for building.

From older commit no longer required

* 0001-avcodec-arm-sbcenc-avoid-callee-preserved-vfp-regist.patch
* 0002-Fix-build-on-powerpc-and-ppc64.patch
* 0003-avcodec-pngenc-remove-monowhite-from-apng-formats.patch
* 0004-ffmpeg-4.3.4-rpi_14.patc
* 0005-fix-flags.diff

Created by OE community to fix builds and are no longer required

* 2002-libavdevice-opengl_enc-update-dynamic-function-loader.patch
* 2003-libavcodec-fix-v4l2_req_devscan.patch

rpidistro-ffmpeg updates:

* removal of avresample flag. No longer exists
* removal of rpi flag. No longer exists
* include vout-egl and epoxy if opengl or x11 included
  in DISTRO_FEATURES.

Signed-off-by: Vincent Davis Jr <vince@underview.tech>