ASoC: soc-compress: avoid false-positive Wuninitialized warning

gcc-6.5 and earlier show a new warning:

sound/soc/soc-compress.c: In function ‘soc_compr_open’:
sound/soc/soc-compress.c:75:28: warning: ‘component’ is used uninitialized in this function [-Wuninitialized]
  struct snd_soc_component *component, *save = NULL;
                              ^~~~~~~~~

Simplest fix is to initialize it to avoid the warning.
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Rong Chen <rong.a.chen@intel.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/lkml/202004201540.vYPhhYMs%25lkp@intel.com
Link: https://lore.kernel.org/r/20200424005437.3941-1-rong.a.chen@intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-compress.c

@@ -72,7 +72,7 @@ static int soc_compr_components_free(struct snd_compr_stream *cstream,
 static int soc_compr_open(struct snd_compr_stream *cstream)
 {
 	struct snd_soc_pcm_runtime *rtd = cstream->private_data;
-	struct snd_soc_component *component, *save = NULL;
+	struct snd_soc_component *component = NULL, *save = NULL;
 	struct snd_soc_dai *cpu_dai = asoc_rtd_to_cpu(rtd, 0);
 	int ret, i;