nitrogen6x: 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.

Cc: Eric Nelson <eric.nelson@boundarydevices.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
diff --git a/board/boundary/nitrogen6x/nitrogen6x.c b/board/boundary/nitrogen6x/nitrogen6x.c
index fcd4d82..e8ea256 100644
--- a/board/boundary/nitrogen6x/nitrogen6x.c
+++ b/board/boundary/nitrogen6x/nitrogen6x.c
@@ -302,7 +302,7 @@
 
 int board_mmc_init(bd_t *bis)
 {
-	s32 status = 0;
+	int ret;
 	u32 index = 0;
 
 	usdhc_cfg[0].sdhc_clk = mxc_get_clock(MXC_ESDHC3_CLK);
@@ -325,13 +325,15 @@
 		       printf("Warning: you configured more USDHC controllers"
 			       "(%d) then supported by the board (%d)\n",
 			       index + 1, CONFIG_SYS_FSL_USDHC_NUM);
-		       return status;
+		       return -EINVAL;
 		}
 
-		status |= fsl_esdhc_initialize(bis, &usdhc_cfg[index]);
+		ret = fsl_esdhc_initialize(bis, &usdhc_cfg[index]);
+		if (ret)
+			return ret;
 	}
 
-	return status;
+	return 0;
 }
 #endif