gpsd: fix warning about overwritting keys

* WARNING: Variable key FILES_${PN}-dev (${includedir} ${FILES_SOLIBSDEV} ${libdir}/*.la ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig ${datadir}/aclocal ${base_libdir}/*.o ${libdir}/${BPN}/*.la ${base_libdir}/*.la) replaces original key FILES_gpsd-dev ( ${libdir}/pkgconfdir/libgpsd.pc ${libdir}/pkgconfdir/libgps.pc).

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>