Add inarp to base image

Add the inarp package to the base image. If users later want
to turn it off and not have it be part of the base image,
it can be changed to a distro spec then.
diff --git a/meta-phosphor/classes/obmc-phosphor-image.bbclass b/meta-phosphor/classes/obmc-phosphor-image.bbclass
index 0d4a0d0..164da33 100644
--- a/meta-phosphor/classes/obmc-phosphor-image.bbclass
+++ b/meta-phosphor/classes/obmc-phosphor-image.bbclass
@@ -41,6 +41,7 @@
         packagegroup-obmc-phosphor-apps-extras \
         i2c-tools \
         screen \
+        inarp \
         "
 
 def build_overlay(d):