This commit cleanups the use of function: failed().
The new function name is: failure(), and it is used
for print errno and the errno-related message only.

The second change is choosing PMIC device by it's name,
instead of seq number. Thanks to this change, for set
the current device, call of pmic_get() is enough.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested on sandbox:
Tested-by: Simon Glass <sjg@chromium.org>

This is new command for the PMIC devices based on driver model PMIC API.
Command features are unchanged:
- list UCLASS pmic devices
- show or [set] operating pmic device (NEW)
- dump registers
- read byte of register at address
- write byte to register at address

The only one change for this command is 'dev' subcommand.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>