ASoC: fsl_asrc: Use 'ifdef' for config options

Fix the following build errors that were observed by building with
make ARCH=microblaze allyesconfig:

>> sound/soc/fsl/fsl_asrc.c:906:5: warning: "CONFIG_PM_RUNTIME" is not defined [-Wundef]
    #if CONFIG_PM_RUNTIME
        ^
>> sound/soc/fsl/fsl_asrc.c:934:5: warning: "CONFIG_PM_SLEEP" is not defined [-Wundef]
    #if CONFIG_PM_SLEEP
        ^
>> sound/soc/fsl/fsl_asrc.c:906:5: warning: "CONFIG_PM_RUNTIME" is not defined [-Wundef]
    #if CONFIG_PM_RUNTIME
        ^
>> sound/soc/fsl/fsl_asrc.c:934:5: warning: "CONFIG_PM_SLEEP" is not defined [-Wundef]
    #if CONFIG_PM_SLEEP

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>