serial: imx: initialize the local variable

The slave_config is not initialized, so some of its fields may
be set with random data which may causes the failure in the following
dmaengine_prep_slave_sg().

This patch fixes this issue.

Signed-off-by: Huang Shijie <b32955@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 2c13155..a0ebbc9 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -979,7 +979,7 @@
 
 static int imx_uart_dma_init(struct imx_port *sport)
 {
-	struct dma_slave_config slave_config;
+	struct dma_slave_config slave_config = {};
 	struct device *dev = sport->port.dev;
 	int ret;