coresight tmc etr: Fix uninitialised variable

Variable 'paddr' can't be used if uninitialised but is nonetheless
confusing to some static checker.  As such simply initialise it to zero.
Reported-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hwtracing/coresight/coresight-tmc-etr.c

@@ -113,7 +113,7 @@ static int tmc_enable_etr_sink_sysfs(struct coresight_device *csdev)
 	bool used = false;
 	unsigned long flags;
 	void __iomem *vaddr = NULL;
-	dma_addr_t paddr;
+	dma_addr_t paddr = 0;
 	struct tmc_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);