ASoC: cs4270: Check that we can enable regulators on resume

It's possible that the regulator enable will fail and if it does we may
as well just give up with trying to bring the rest of the device up and
report the original error.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Timur Tabi <timur@freescale.com>