cros: Update ec_commands to latest version

This file has changed quite a bit in the last 5 years as the capabilities
of the ECs have grown. Sync it up with the copy in coreboot commit
b9141f2215.

The only change is the addition of EC_VBNV_BLOCK_SIZE_V2. This is needed
because U-Boot uses the new v2 vboot API and this is not currently fully
supported by Chromium OS firmware.

Signed-off-by: Simon Glass <sjg@chromium.org>