Unify ERROR buffer size with TRACE buffer

Signed-off-by: Stefano Babic <sbabic@denx.de>
Use revision strings instead of major.minor

Boards have often a more complicated schema
to identify itself with a revision number. The
simple way with two integers for a major.minor
revision is not suitable for that purposes.
Replace them with a string, that identify the
revision for a board. The Hardware compatibility
file must have the format:
	<target name>	<target revision string>

Only one entry is allowed and read by the parser.
Further entries are ignored.

Signed-off-by: Stefano Babic <sbabic@denx.de>
Handling configuration differences

Add support for having a single image containing
the software for multiple devices. Support is
added to the libconfig parser.

The resulting image is then realized as the concatenation
of multiple images, one for each single device.
Files inside the whole image must have unique filenames.

sw-description is extended to have an entry for each target.

software =
{
	version = "0.1.0";

	target-1 = {
		images: (
			{
				...
			}
		);
	};

	target-2 = {
		images: (
			{
				...
			}
		);
	};
}

Previous format is still supported. If there is not an entry
of type software.<board name>.<field>, the parser falls back
to software.<field>

Signed-off-by: Stefano Babic <sbabic@denx.de>