ASoC: rt5640: Don't go to standby on resume

There is no need for the CODEC to go to standby on resume since the core will
power it up as needed and in any case it is an idle_bias_off CODEC so would
normally sit with bias off while idle.

Signed-off-by: Mark Brown <broonie@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>