fp5280g2: Load LED manager with JSON configuration

Since the led manager used the default YAML to generated led-gen.hpp and
creates D-Bus object for the groups, and we tend to use JSON instead of
YAML to create it.

Tested: built successfully on phosphor-led-manager and create D-Bus
object used JSON configuration.

(From meta-inspur rev: 911c71c43beb4a3696f5c846bee06bc0a0d7bab2)

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: Ibc72f26519bb968ed4b4c8df4e068206ab9c0704
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>