gpsd: s/gpsd-dev/${PN}-dev to make bitbake happy

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: Marcin Juszkiewicz <marcin.juszkiewicz@linaro.org>