fp5280g2: leds: Use PACKAGECONFIG_append instead of EXTRA_OECONF

- Since the phosphor-led-manager_git.bb file use PACKAGECONFIG to
  define `use-json`, should use PACKAGECONFIG_append instead of
  EXTRA_OECONF.

Tested: Built ledManager successfully and saw use the JSON
        configuration file at runtime than the static led.yaml

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: I91039207176e483bd83e670b1a2d72a58c7ff2e6
diff --git a/meta-inspur/meta-fp5280g2/recipes-phosphor/leds/phosphor-led-manager_%.bbappend b/meta-inspur/meta-fp5280g2/recipes-phosphor/leds/phosphor-led-manager_%.bbappend
index 2ad194f..5bae926 100644
--- a/meta-inspur/meta-fp5280g2/recipes-phosphor/leds/phosphor-led-manager_%.bbappend
+++ b/meta-inspur/meta-fp5280g2/recipes-phosphor/leds/phosphor-led-manager_%.bbappend
@@ -2,7 +2,7 @@
 
 SRC_URI += "file://led-group-config.json"
 
-EXTRA_OECONF += "--enable-use-json"
+PACKAGECONFIG_append = " use-json"
 
 DEPENDS += "phosphor-dbus-interfaces"