mx51evk: Fix error handling in board_mmc_init()

When an invalid USDHC port is passed we should return -EINVAL instead of 0.

Also, return the error immediately on fsl_esdhc_initialize() failure.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/freescale/mx51evk/mx51evk.c b/board/freescale/mx51evk/mx51evk.c
index 9b43c84..f1e5eb4 100644
--- a/board/freescale/mx51evk/mx51evk.c
+++ b/board/freescale/mx51evk/mx51evk.c
@@ -320,7 +320,7 @@
 	};
 
 	u32 index;
-	s32 status = 0;
+	int ret;
 
 	esdhc_cfg[0].sdhc_clk = mxc_get_clock(MXC_ESDHC_CLK);
 	esdhc_cfg[1].sdhc_clk = mxc_get_clock(MXC_ESDHC2_CLK);
@@ -340,11 +340,13 @@
 			printf("Warning: you configured more ESDHC controller"
 				"(%d) as supported by the board(2)\n",
 				CONFIG_SYS_FSL_ESDHC_NUM);
-			return status;
+			return -EINVAL;
 		}
-		status |= fsl_esdhc_initialize(bis, &esdhc_cfg[index]);
+		ret = fsl_esdhc_initialize(bis, &esdhc_cfg[index]);
+		if (ret)
+			return ret;
 	}
-	return status;
+	return 0;
 }
 #endif