projects/RPi/patches/linux: update RPi support patch

Signed-off-by: Stephan Raue <stephan@openelec.tv>
libdrm: update to libdrm-2.4.56

Signed-off-by: Stephan Raue <stephan@openelec.tv>
ffmpeg: update to ffmpeg-2.3.1

Signed-off-by: Stephan Raue <stephan@openelec.tv>