faad2: fix QA warnings

fix the following warnings:
WARNING: QA Issue: non -staticdev package contains static .a library: libfaad-dev path '/work/armv7a-angstrom-linux-gnueabi/faad2-2.7-r1/packages-split/libfaad-dev/usr/lib/libfaad.a'
WARNING: QA Issue: non -staticdev package contains static .a library: libmp4ff-dev path '/work/armv7a-angstrom-linux-gnueabi/faad2-2.7-r1/packages-split/libmp4ff-dev/usr/lib/libmp4ff.a'

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net>