raspberrypi inclusion
category: feature
bugzilla: 50432

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Now that we can export deeper colour depths, add in the signalling
for HDR metadata.
Signed-off-by: NDave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>