board: dragonboard410c: Use button_cmd instead of custom code

board: dragonboard410c: Use button_cmd instead of custom code

Simplify the board code by using the new BUTTON_CMD functionality, instead
of implementing this separately using C code. This allows disabling or
customizing this functionality if wanted.

Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by:
Link: https://lore.kernel.org/r/20250407-db410c-fixes-v1-12-524aefbc8bb4@linaro.org
Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>