staging: drm/imx: replace IS_ERR and PTR_ERR with PTR_ERR_OR_ZERO

This patch fixes coccinelle error regarding usage of IS_ERR and
PTR_ERR instead of PTR_ERR_OR_ZERO.
Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Reviewed-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -359,10 +359,8 @@ static int imx_ldb_get_clk(struct imx_ldb *ldb, int chno)
 
 	sprintf(clkname, "di%d_pll", chno);
 	ldb->clk_pll[chno] = devm_clk_get(ldb->dev, clkname);
-	if (IS_ERR(ldb->clk_pll[chno]))
-		return PTR_ERR(ldb->clk_pll[chno]);
 
-	return 0;
+	return PTR_ERR_OR_ZERO(ldb->clk_pll[chno]);
 }
 
 static int imx_ldb_register(struct imx_ldb_channel *imx_ldb_ch)