asoc/multi-component: fsl: add support for disabled SSI nodes

Add support for adding "status = disabled" to an SSI node to incidate that it
is not wired on the board.  This replaces the not-so-intuitive previous method
of omitting a codec-handle property.

Signed-off-by: Timur Tabi <timur@freescale.com>
Acked-by: Kumar Gala <galak@kernel.crashing.org>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>