samples: lightdb_led: bring back "LED <num> -> <value>" info log

[mniestroj]

This message is mentioned as part of README.rst and is very useful for verifying if LED values are received correctly. This is especially important for qemu_x86.

This brings back behavior before commit f72c094fe1f3 ("samples: lightdb_led: convert from TinyCBOR to QCBOR") was merged.

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 0bdb9e4):

https://golioth-zephyr-sdk-doxygen-dev--pr267-samples-lightdb-t5mvvr7e.web.app

_{(expires Thu, 08 Sep 2022 13:40:01 GMT)}

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