Merge patch series "cmd: add scmi command"

To quote the author:

"Scmi" command will be re-introduced per Michal's request.
The functionality is the same as I put it in my patch set of adding
SCMI base protocol support, but made some tweak to make UT, "ut dm
scmi_cmd," more flexible and tolerable when enabling/disabling a specific
SCMI protocol for test purpose.

Each commit may have some change history inherited from the preceding
patch series.

Test
====
The patch series was tested on the following platforms:
* sandbox

diff --cc cmd/Kconfig
Simple merge

diff --cc cmd/Makefile
Simple merge

diff --cc configs/sandbox_defconfig
Simple merge