Allow pin name parameter for pimux staus command,
as gpio command to get status of one pin.
The possible usage of the command is:
> pinmux dev pinctrl
> pinmux status
> pinmux status -a
> pinmux status <pin-name>
Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
