ASoC: ab8500: Remove explicit initialization of driver callbacks to NULL

Fields of structs with global storage are implicitly initialized to 0/NULL,
there is usually no need to do this explicitly.

Removing the initialization of the legacy suspend/resume callback fields
also gets the driver ready for the day when they are eventually removed.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/ab8500-codec.c

@@ -2587,8 +2587,6 @@ static struct platform_driver ab8500_codec_platform_driver = {
 	},
 	.probe		= ab8500_codec_driver_probe,
 	.remove		= ab8500_codec_driver_remove,
-	.suspend	= NULL,
-	.resume		= NULL,
 };
 module_platform_driver(ab8500_codec_platform_driver);