ASoC: remove a card from the list, if instantiation failed

If instantiation of a card failed, we still have to remove it from the
card list on unregistration. This fixes an Oops on Migo-R, triggering,
when after a failed firmware load attempt the driver modules are removed
and re-inserted again.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>