Modify the return code with using macro

bsp/mini2440/drivers/sdcard.c

@@ -574,7 +574,7 @@ int rt_hw_sdcard_init(void)
         {
             rt_kprintf("allocate partition sector buffer failed\n");
 
-            return -1;
+            return -RT_ERROR;
         }
         status = sd_readblock(0, sector);
         if (status == RT_EOK)
@@ -637,7 +637,7 @@ int rt_hw_sdcard_init(void)
         /* release sector buffer */
         rt_free(sector);
 
-        return -1; 
+        return -RT_ERROR; 
     }
     else
     {

bsp/mini2440/drivers/uart.c

@@ -196,7 +196,7 @@ int rt_hw_uart_init(void)
     rt_hw_interrupt_install(_hwserial2.irqno, rt_hw_uart_isr, &_serial2, "uart2");
     rt_hw_interrupt_umask(INTUART2);
 
-    return 0;
+    return RT_EOK;
 }
 
 INIT_BOARD_EXPORT(rt_hw_uart_init);