ec_commands: Add commands required for EC-EC communication
ec_commands: Add commands required for EC-EC communication

This adds 3 commands to obtain static and dynamic battery
information, as well as control base charger state.

These host commands are meant to be used as part of the EC-EC
communication protocol (based on hostcmd v4 protocol), but could
be used in the future to pass information between AP and EC,
especially when more than 1 battery is present, which would be
hard to support with the current MEMMAP-based approach.

BRANCH=none
BUG=b:65697962
BUG=b:65697620
TEST=Build wand and lux boards, flash it, EC-EC communication works.

Signed-off-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>
Change-Id: I263454794394838918832c9e4623835ab2f3a3da
Reviewed-on: https://chromium-review.googlesource.com/670380
Reviewed-by: Vincent Palatin <70a9964ec8fd10b0b08fcc8623c2add25ddf99ac@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec