ARM: dts: orion5x-lschl: Fix model name

Model name should be consistent with legacy device file, so that user
can migrate their system from legacy device support to device-tree
safely.

Legacy device file is currently removed, but it can be found on 4.8
or previous version of linux:
  arch/arm/mach-orion5x/ls-chl-setup.c

Fixes: f94f268979a2 ("ARM: dts: orion5x: convert ls-chl to FDT")
Cc: Ashley Hughes <ashley.hughes@blueyonder.co.uk>
Signed-off-by: Roger Shimizu <rogershimizu@gmail.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>