unit-test.py: define hei pkg-config association

Associate hei pkg-config module with openpower-libhei so that the hei
library will be installed and availble as a build time dependency.

Signed-off-by: Ben Tyner <ben.tyner@ibm.com>
Change-Id: I450026c64fab6c08dd299fd43ed1ad2f91373ec2
diff --git a/scripts/unit-test.py b/scripts/unit-test.py
index bbc24ff..45f4b98 100755
--- a/scripts/unit-test.py
+++ b/scripts/unit-test.py
@@ -1034,6 +1034,7 @@
             'phosphor-logging': 'phosphor-logging',
             'phosphor-snmp': 'phosphor-snmp',
             'ipmiblob': 'ipmi-blob-tool',
+            'hei': 'openpower-libhei',
         },
     }