coresight: Initialize arg in sparse friendly way

Sparse gets annoyed when this initializer is 0 but the first struct
member is a pointer. Just use { } to initialize instead so that sparse
is quiet.

Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20200518180242.7916-19-mathieu.poirier@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-etm3x.c

@@ -504,7 +504,7 @@ static int etm_enable_perf(struct coresight_device *csdev,
 static int etm_enable_sysfs(struct coresight_device *csdev)
 {
 	struct etm_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
-	struct etm_enable_arg arg = { 0 };
+	struct etm_enable_arg arg = { };
 	int ret;
 
 	spin_lock(&drvdata->spinlock);

drivers/hwtracing/coresight/coresight-etm4x.c

@@ -412,7 +412,7 @@ static int etm4_enable_perf(struct coresight_device *csdev,
 static int etm4_enable_sysfs(struct coresight_device *csdev)
 {
 	struct etmv4_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
-	struct etm4_enable_arg arg = { 0 };
+	struct etm4_enable_arg arg = { };
 	int ret;
 
 	spin_lock(&drvdata->spinlock);