package/ffmpeg: Re-number patch 0014 to 0015

Got it wrong in
http://git.buildroot.net/buildroot/commit/?id=032e2beedfe7f503f0686470ae930d4c8b41b780



Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>