[dev][acpi] Translate AE_OK to ZX_OK

This effects several callers of this function that expect it to
translate AE_OK, and not just the failure values.

Test: Boot garnet on NUC and vim2

Change-Id: Ia8be51c2619ecf270ebe03210896712ac4b3f3bb

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[dev][acpi] add support for battery and power source devices

Batteries and power source devices (e.g. AC adapters) are
published under /dev/class/power. These devices support
the following ioctls:

IOCTL_POWER_GET_INFO returns the type of the device and
its status.

IOCTL_POWER_GET_BATTERY_INFO is only supported by
batteries. It returns battery status such as capacity
and voltage.

IOCTL_POWER_GET_STATE_CHANGE_EVENT returns an event the
client can use to receive power state change events. When
the state is changed MX_USER_SIGNAL_0 is raised on the
event. Reading the state with IOCTL_POWER_GET_INFO clears
the signal.

Refer to magenta/device/power.h for more information on
the API.

Add the 'lspwr' utility to show information about power
devices.

Change-Id: Ic354402541659b11693184353e3f5d1deac8a129