ASoC: fsl: Use #ifdef instead of #if for CONFIG_PM_SLEEP

Change them to #ifdef as CONFIG_PM_SLEEP might not be defined at all.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>