meta-facebook: yosemite4: enable obmc-phosphor-buttons support

Support OCP debug card use in the yosemite4 system.

Change-Id: I72a4b20a3241e1097dc3fcb053afa4362ee2b370
Signed-off-by: Delphine CC Chiu <Delphine_CC_Chiu@wiwynn.com>
diff --git a/meta-facebook/meta-yosemite4/recipes-phosphor/images/fb-yosemite4-phosphor-image.inc b/meta-facebook/meta-yosemite4/recipes-phosphor/images/fb-yosemite4-phosphor-image.inc
index 2b5727e..16a77f6 100644
--- a/meta-facebook/meta-yosemite4/recipes-phosphor/images/fb-yosemite4-phosphor-image.inc
+++ b/meta-facebook/meta-yosemite4/recipes-phosphor/images/fb-yosemite4-phosphor-image.inc
@@ -14,9 +14,11 @@
 OBMC_IMAGE_EXTRA_INSTALL:append = " \
     plat-svc \
 "
-
+# Enable obmc-phosphor-buttons which needed by debug card function.
 OBMC_IMAGE_EXTRA_INSTALL:append = " \
     phosphor-gpio-monitor \
+    obmc-phosphor-buttons-signals \
+    obmc-phosphor-buttons-handler \
 "
 
 # This enables the feature of dbus-monitor which defined in