Indicating error message when failed case is very useful for debuging.
In many case, its style is like below.

	int function(...)
	{
		...
		return ret;
	}

	int caller(...)
	{
		...
		ret = function(...);
		if (ret < 0)
			dev_err(...)
		...
	}

This is not so bad, but in this style *each caller* needs to indicate
duplicate same error message, and some caller is forgetting to do it.
And caller can't indicate detail function() error information.

If function() indicates error message, we can get same and
detail information without forgot.

	int function(...)
	{
		...
		if (ret < 0)
			dev_err(...)

		return ret;
	}

	int caller(...)
	{
		...
		ret = function(...);
		...
	}

This patch also
do below to dpcm_run_update_startup()
	1) remove duplicated ret = -EINVAL
	2) remove blank line
do below to dpcm_run_update_shutdown()
	1) remove unused ret
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87im5tutb3.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>