Merge branch 'tools-ynl-add-schema-checking'

Donald Hunter says:

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tools: ynl: add schema checking

Add schema checking and yaml linting for the YNL specs.

Patch 1 adds a schema_check make target using a pyynl --validate option
Patch 2 adds a lint make target using yamllint
Patches 3,4 fix issues reported by make -C tools/net/ynl lint schema_check
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Link: https://patch.msgid.link/20251127123502.89142-1-donald.hunter@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>