MIPS: lantiq: copy the commandline from the devicetree

This is a regression caused by:
commit afb46f7996e91aeb36e07bc92cf96e8045bec00e
Author: Rob Herring <robh@kernel.org>
Date:   Wed Apr 2 19:07:24 2014 -0500
mips: ralink: convert to use unflatten_and_copy_device_tree

Make the of init code reuse the cmdline defined inside the dts.

Signed-off-by: John Crispin <blogic@openwrt.org>
Patchwork: http://patchwork.linux-mips.org/patch/8048/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/lantiq/prom.c

@@ -77,6 +77,8 @@ void __init plat_mem_setup(void)
 	 * parsed resulting in our memory appearing
 	 */
 	__dt_setup_arch(__dtb_start);
+
+	strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);
 }
 
 void __init device_tree_init(void)