keys: add device specific implementation

For real target devices there is only a small subset of keys we're able to use. This is
known handled and mapped within a device specific implementation which is separated from
the emulator one.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
led_controller: initial code for a common led controller module

The current implementation only provides support for setting the backlight brightness and
disabling/enabling the backlight when needed. Further effect implementation is missing.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
touchpanel: rename emulator implementation to evdev

The current emulator implementation is using the evdev input protocol which is appropiate
for other devices as well so we make it unrelated to the emulator here. Differences
between different target machines (and emulator) should be implemented as config options.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
touchpanel: evdev: read screen size from framebuffer when possible

* read screen size when not defined by machine config from framebuffer
* define static screen size for qemuarm and qemux86 machines

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
touchpanel: build evdev implementation for WEBOS_TARGET_MACHINE_IMPL device

The evdev implementation should be suitable for most devices until we have a real multi
touch implementation for the MT protocol.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
system: use a flat directory structure to have same code for all machines

If there need to be specific implementations for different machines then this should be
separated from the main module code which should mostly be the same for all needed
implementations.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
battery: split out common file handling methods into separate source file

Having common functionality separated from the specific ones makes it easier to implement
for a target device which is not the emulator. Both can still share the same common
functionality.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
battery: add a device specific implementation

The implementation is based on the common linux power supply interface and is detected
changes to the current status with processing uevents due to the use of libudev.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
charger: split out common module functionality

With splitting out common module functionality we're now able to add different
implementations for the charger module. For target emulator machines this is still the
same dummy implementation as before.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
charger: add a device implementation for charger status detection

The device implementation is based on the common linux power supply interface and is per
default enabled to detect changes for AC and USB chargers. It's using libudev to detect
a changed charger status.

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>
machine: add support for the tuna machine

Open-webOS-DCO-1.0-Signed-off-by: Simon Busch <morphis@gravedo.de>