configure: Factorize qsv dependencies

configure

@@ -2253,6 +2253,7 @@ wmv3_vdpau_hwaccel_select="vc1_vdpau_hwaccel"
 nvenc_deps_any="libdl LoadLibrary"
 omx_deps="libdl pthreads"
 omx_rpi_select="omx"
+qsv_deps="libmfx"
 qsvdec_select="qsv"
 qsvenc_select="qsv"
 vaapi_encode_deps="vaapi"
@@ -2263,33 +2264,25 @@ scale_npp_filter_deps="cuda libnpp"
 h264_mmal_decoder_deps="mmal"
 h264_nvenc_encoder_deps="nvenc"
 h264_omx_encoder_deps="omx"
-h264_qsv_decoder_deps="libmfx"
 h264_qsv_decoder_select="h264_mp4toannexb_bsf h264_parser qsvdec h264_qsv_hwaccel"
-h264_qsv_encoder_deps="libmfx"
 h264_qsv_encoder_select="qsvenc"
 h264_vaapi_encoder_deps="VAEncPictureParameterBufferH264"
 h264_vaapi_encoder_select="vaapi_encode golomb"
 hevc_nvenc_encoder_deps="nvenc"
-hevc_qsv_decoder_deps="libmfx"
 hevc_qsv_decoder_select="hevc_mp4toannexb_bsf hevc_parser hevc_qsv_hwaccel qsvdec"
-hevc_qsv_encoder_deps="libmfx"
 hevc_qsv_encoder_select="hevc_ps qsvenc"
 hevc_vaapi_encoder_deps="VAEncPictureParameterBufferHEVC"
 hevc_vaapi_encoder_select="vaapi_encode golomb"
 mjpeg_vaapi_encoder_deps="VAEncPictureParameterBufferJPEG"
 mjpeg_vaapi_encoder_select="vaapi_encode jpegtables"
 mpeg2_mmal_decoder_deps="mmal"
-mpeg2_qsv_decoder_deps="libmfx"
 mpeg2_qsv_decoder_select="qsvdec mpeg2_qsv_hwaccel mpegvideo_parser"
-mpeg2_qsv_encoder_deps="libmfx"
 mpeg2_qsv_encoder_select="qsvenc"
 mpeg2_vaapi_encoder_deps="VAEncPictureParameterBufferMPEG2"
 mpeg2_vaapi_encoder_select="vaapi_encode"
 mpeg4_omx_encoder_deps="omx"
 vc1_mmal_decoder_deps="mmal"
-vc1_qsv_decoder_deps="libmfx"
 vc1_qsv_decoder_select="qsvdec vc1_qsv_hwaccel vc1_parser"
-vp8_qsv_decoder_deps="libmfx"
 vp8_qsv_decoder_select="qsvdec vp8_qsv_hwaccel vp8_parser"
 vp8_vaapi_encoder_deps="VAEncPictureParameterBufferVP8"
 vp8_vaapi_encoder_select="vaapi_encode"