cmd_bootm.c: Do not load a ramdisk when not booting a kernel.

In case we boot an image marked as 'standalone' and 'linux', the current
code erroneously tried to load a ramdisk.
Signed-off-by: NDetlev Zundel <dzu@denx.de>

common/cmd_bootm.c

@@ -293,7 +293,8 @@ static int bootm_start(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
 		return 1;
 	}
 
-	if (images.os.os == IH_OS_LINUX) {
+	if ((images.os.type == IH_TYPE_KERNEL) &&
+	    (images.os.os == IH_OS_LINUX)) {
 		/* find ramdisk */
 		ret = boot_get_ramdisk (argc, argv, &images, IH_INITRD_ARCH,
 				&images.rd_start, &images.rd_end);