common/cmd_source.c: Fix the source command failure under 64-bit platform

Modify the data pointer type from ulong* to u32*.

For arm64 type "ulong" could be 64-bit. Then in line 89 of common/cmd_source.c:
"while (*data++);" data will point to the next 64 bits each time. As the uImage
file generated by mkimage tool keeps the same data format in either 32-bit or 64-bit
platform, the difference would cause failure in 64-bit platform.

Signed-off-by: Gong Qianyu <Qianyu.Gong@freescale.com>

common/cmd_source.c

@@ -33,7 +33,7 @@ source (ulong addr, const char *fit_uname)
 #if defined(CONFIG_IMAGE_FORMAT_LEGACY)
 	const image_header_t *hdr;
 #endif
-	ulong		*data;
+	u32		*data;
 	int		verify;
 	void *buf;
 #if defined(CONFIG_FIT)
@@ -74,7 +74,7 @@ source (ulong addr, const char *fit_uname)
 		}
 
 		/* get length of script */
-		data = (ulong *)image_get_data (hdr);
+		data = (u32 *)image_get_data (hdr);
 
 		if ((len = uimage_to_cpu (*data)) == 0) {
 			puts ("Empty Script\n");
@@ -128,7 +128,7 @@ source (ulong addr, const char *fit_uname)
 			return 1;
 		}
 
-		data = (ulong *)fit_data;
+		data = (u32 *)fit_data;
 		len = (ulong)fit_len;
 		break;
 #endif