fdt: fix extend of cmd line

On arm CONFIG_CMDLINE_EXTEND does not append build-in
cmdline in kernel to U-boot parameters. Fix it here.
Theoretically this patch should repair kdump work where
it adds elfcorehdr= and memmap additional parameters
to second kernel.
Signed-off-by: NMax Uvarov <muvarov@gmail.com>
Signed-off-by: NRob Herring <robh@kernel.org>

drivers/of/fdt.c

@@ -969,10 +969,16 @@ int __init early_init_dt_scan_chosen(unsigned long node, const char *uname,
 	 * is set in which case we override whatever was found earlier.
 	 */
 #ifdef CONFIG_CMDLINE
-#ifndef CONFIG_CMDLINE_FORCE
+#if defined(CONFIG_CMDLINE_EXTEND)
+	strlcat(data, " ", COMMAND_LINE_SIZE);
+	strlcat(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+#elif defined(CONFIG_CMDLINE_FORCE)
+	strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+#else
+	/* No arguments from boot loader, use kernel's  cmdl*/
 	if (!((char *)data)[0])
-#endif
 		strlcpy(data, CONFIG_CMDLINE, COMMAND_LINE_SIZE);
+#endif
 #endif /* CONFIG_CMDLINE */
 
 	pr_debug("Command line is: %s\n", (char*)data);