This patch is a device tree enhancement that IMHO is worthy of mainline.
It allows the bootloader's commandline to be preserved even when the
device tree specifies one.

Signed-off-by: Daniel Gimpelevich <daniel@gimpelevich.san-francisco.ca.us>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@36780 3c298f89-4303-0410-b956-a3cf2f4a3e73