kdb: Remove redundant function definitions/prototypes

Cleanup kdb code to get rid of unused function definitions/prototypes.

Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lore.kernel.org/r/20210224071653.409150-1-sumit.garg@linaro.org


Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>