chg: Force charge FET on during charging

Because we must force current into the gas gauge to get it to charge,
we must also force the charge FET on.  Otherwise, the charger will be
on but no current will flow to the gas gauge.

Signed-off-by: Sean Cross <xobs@kosagi.com>
cmd-gpio: Add functions to read/set/clear IRQ GPIO

This is for testing the IRQ pin.

Signed-off-by: Sean Cross <xobs@kosagi.com>
main: Simplify power button logic

Rather than using a state tree, simply ask "is the button armed?"  If so,
do the current action (suspend or power off) and disarm the button.

Signed-off-by: Sean Cross <xobs@kosagi.com>
senoko-shell: Add cmd_power

This lets us see if the mainboard is "on" or not.

Signed-off-by: Sean Cross <xobs@kosagi.com>