media: dt-bindings: st,stm32-cec: drop obsolete file

The st,stm32-cec.yaml was moved to media/cec directory, however the
"remove" part disappeared during applying.

Link: https://lore.kernel.org/all/20221208103115.25512-3-krzysztof.kozlowski@linaro.org/



Fixes: 8f437662 ("media: dt-bindings: st,stm32-cec: move to cec subfolder")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>