README: Update I2C register listings

We now separate keyboards, AC plugs, and GPIOs into their own blocks.

Signed-off-by: Sean Cross <xobs@kosagi.com>
senoko-slave: Use new I2C register blocks

Now that the regulator (AC plug), power button (keyboard), and GPIOs
are all different "blocks", update the I2C slave block to reflect this.

Signed-off-by: Sean Cross <xobs@kosagi.com>
gg: Make sure we return error on timeout

When there's a timeout, we used to return 0.  Now return an error.

Signed-off-by: Sean Cross <xobs@kosagi.com>
chg: Pay attention to status, and ensure DSG fet is on

If the DSG FET needs to be turned off, manually turn it off.  Otherwise,
manually turn it on.  We need to do this because we're doing some things
by hand, including managing the CHG/DSG FETs.

Signed-off-by: Sean Cross <xobs@kosagi.com>
power: Disable power_testing (let the board turn off)

We're reasonably certian power management works now, so allow Senoko to
power off the mainboard now.

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