imx-drm: imx-ldb: Use snprintf()

Use snprintf() in order to fix the following static checker warning:

drivers/staging/imx-drm/imx-ldb.c:340 imx_ldb_get_clk() error: format string overflow. buf_size: 16 length: 18
probably 18 is theory and not real life, but 16 is based on
theory as well.
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/imx-drm/imx-ldb.c

@@ -334,12 +334,12 @@ static int imx_ldb_get_clk(struct imx_ldb *ldb, int chno)
 {
 	char clkname[16];
 
-	sprintf(clkname, "di%d", chno);
+	snprintf(clkname, sizeof(clkname), "di%d", chno);
 	ldb->clk[chno] = devm_clk_get(ldb->dev, clkname);
 	if (IS_ERR(ldb->clk[chno]))
 		return PTR_ERR(ldb->clk[chno]);
 
-	sprintf(clkname, "di%d_pll", chno);
+	snprintf(clkname, sizeof(clkname), "di%d_pll", chno);
 	ldb->clk_pll[chno] = devm_clk_get(ldb->dev, clkname);
 
 	return PTR_ERR_OR_ZERO(ldb->clk_pll[chno]);