dut_power: add option to not query EC vbat

Add an option to dut-power tool to not query EC vbat. This is
helpful when measuring standby power where querying EC vbat
constantly increases total power.

BUG=chromium:806146, b:111616837
TEST=manual testing

sudo servod -b nami -c nami_rev1_inas.xml

dut-power -h
shows the help message

dut-power
works, provide both INA and EC data

dut-power --ina-rate=-1 --vbat-rate=-1
works, throws exception as expected

dut-power --ina-rate=1 --vbat-rate=-1
works, only query ina

dut-power --ina-rate=-1 --vbat-rate=1
works, only query EC

Change-Id: I29c5ec3d7bcd578aea0c7463b1b646cd733b48cd
Signed-off-by: Mengqi Guo <mqg@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1235137
Reviewed-by: Puthikorn Voravootivat <puthik@chromium.org>
Reviewed-by: Todd Broch <tbroch@chromium.org>
2 files changed