ASoC: Intel: fix sparse non static symbol warnings

Fixes the following sparse warnings:

sound/soc/intel/sst/sst_acpi.c:248:5: warning:
 symbol 'sst_acpi_probe' was not declared. Should it be static?
sound/soc/intel/sst/sst_acpi.c:335:5: warning:
 symbol 'sst_acpi_remove' was not declared. Should it be static?
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/intel/sst/sst_acpi.c

@@ -245,7 +245,7 @@ static struct sst_machines *sst_acpi_find_machine(
 	return NULL;
 }
 
-int sst_acpi_probe(struct platform_device *pdev)
+static int sst_acpi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	int ret = 0;
@@ -332,7 +332,7 @@ int sst_acpi_probe(struct platform_device *pdev)
 * This function is called by OS when a device is unloaded
 * This frees the interrupt etc
 */
-int sst_acpi_remove(struct platform_device *pdev)
+static int sst_acpi_remove(struct platform_device *pdev)
 {
 	struct intel_sst_drv *ctx;