ASoC: fsl: imx-pcm-fiq: Remove unused 'runtime' variable

Commit 68f9672b (ASoC: fsl: imx-pcm-fiq: remove bogus period delta calculation)
introduced the following build warning:

sound/soc/fsl/imx-pcm-fiq.c:53:26: warning: unused variable 'runtime' [-Wunused-variable]

Remove the unused 'runtime' variable.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Oskar Schirmer <oskar@scara.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/fsl/imx-pcm-fiq.c

@@ -50,7 +50,6 @@ static enum hrtimer_restart snd_hrtimer_callback(struct hrtimer *hrt)
 	struct imx_pcm_runtime_data *iprtd =
 		container_of(hrt, struct imx_pcm_runtime_data, hrt);
 	struct snd_pcm_substream *substream = iprtd->substream;
-	struct snd_pcm_runtime *runtime = substream->runtime;
 	struct pt_regs regs;
 
 	if (!atomic_read(&iprtd->running))