meta-romulus: Enable image signature check

Change-Id: I05a4bb07a08cc6e89df302b2f25531a665118e1d
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/meta-ibm/meta-romulus/recipes-phosphor/flash/phosphor-software-manager.bbappend b/meta-ibm/meta-romulus/recipes-phosphor/flash/phosphor-software-manager.bbappend
new file mode 100644
index 0000000..c92b1a8
--- /dev/null
+++ b/meta-ibm/meta-romulus/recipes-phosphor/flash/phosphor-software-manager.bbappend
@@ -0,0 +1 @@
+PACKAGECONFIG_append = " verify_signature"