Add tools-profile feature support

With this patch, the build system supports the tools-profile feature,
We can add it into the EXTRA_IMAGE_FEATURES in conf/local.conf,
to add more debug/profile tools into the image

Change-Id: Ic3c3811d9bca3f99a9e94d7c9da5a71ce1321d02
Signed-off-by: Yong Li <yong.b.li@linux.intel.com>
diff --git a/meta-phosphor/conf/layer.conf b/meta-phosphor/conf/layer.conf
index ffccec0..ab0b736 100644
--- a/meta-phosphor/conf/layer.conf
+++ b/meta-phosphor/conf/layer.conf
@@ -11,3 +11,6 @@
 
 # Provide a variable that points the base of the phosphor layer.
 PHOSPHORBASE = '${@os.path.normpath("${LAYERDIR}/")}'
+
+IMAGE_FEATURES[validitems] += "tools-profile"
+