Restrict root user password to obmc-phosphor-image

Restrict root user password to obmc-phosphor-image image recipe.

Change-Id: I00bbfce69128148184c4b2b2029ce25defb939c4
Signed-off-by: Richard Marian Thomaiyar <richard.marian.thomaiyar@linux.intel.com>
diff --git a/conf/distro/include/phosphor-defaults.inc b/conf/distro/include/phosphor-defaults.inc
index 5659215..bac3ad1 100644
--- a/conf/distro/include/phosphor-defaults.inc
+++ b/conf/distro/include/phosphor-defaults.inc
@@ -248,6 +248,6 @@
 # Set the root password to '0penBmc'
 inherit extrausers
 
-EXTRA_USERS_PARAMS = " \
+EXTRA_USERS_PARAMS_pn-obmc-phosphor-image = " \
   usermod -p '\$1\$UGMqyqdG\$FZiylVFmRRfl9Z0Ue8G7e/' root; \
   "