This commit modifies GstVideoMasteringDisplayInfo and GstVideoContentLightLevel
structs so that each value is to be more like hdr_metadata_infoframe struct
of linux drm header and DXGI_HDR_METADATA_HDR10 struct of Windows.
So each value is no more fraction but normalized one as per CTA 861.G spec.
Also the unit of each value will be consistent with H.264, H.265
specifications, hdr_metadata_infoframe struct for linux and
DXGI_HDR_METADATA_HDR10 struct for Windows.
* Fix typo
s/nunormalized/normalized/g
* Update GstVideoMasteringDisplayInfo description
Each values are not array.
* Add missing newline between arguments description and
detailed comment.
Introduce HDR signalling methods
* GstVideoMasteringDisplayInfo: Representing display color volume info.
Defined by SMPTE ST 2086
* GstVideoContentLightLevel: Representing content light level specified in
CEA-861.3, Appendix A.
Closes https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/issues/400
