It is useful to show sensor channels for a battery in cohesive block as
it is easier to read. Add a 'battery' command to handle this. It only
supports a single battery, relying on the device-tree alias to select
it.
uart:~$ battery
Temp: 23.55 C
V: 4.31 V
V-desired: 4.40 V
I: 574 mA (CHG)
I-desired: 2000 mA
Charging: Not Allowed
Charge: 100 %
V-design: 3.86 V
Remaining: 6764 mA
Cap-full: 6764 mA
Design: 6910 mA
Time full: 0h:00
Time empty: 0h:00
Signed-off-by: Simon Glass <sjg@chromium.org>