Introduces a new method of defining channels available from the display,
common to all channel types, allowing for more flexibility in available
channel types/counts, and reducing the amount of boiler-plate required.
This will be required to support Volta.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Engines are initialised on an as-needed basis, so this results in the
same behaviour, whilst allowing us to simplify things a bit.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
