v4l2: add more debug macros to help identifying problems

There are lots of places where caps negotiation may fail.
Add more debug macros to help identifying it.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
8 jobs for add_bayer+debug in 20 minutes and 14 seconds (queued for 53 seconds)
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gst indent

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manifest

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build fedora x86_64

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  Test
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check fedora

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  Full Builds
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build android arm64 api28

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build cerbero cross win32

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build cerbero cross win64

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build cerbero fedora x86_64

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