Fix for fabric.p4 job

- set the basedir of the scm to empty
- fix the branch regex (onos-2.*)

Change-Id: I3fa907bd1cff80b704443f08119a3c6ef7011d54
diff --git a/jjb/repos/fabric-p4.yaml b/jjb/repos/fabric-p4.yaml
index 85c8c6a..f4bc387 100644
--- a/jjb/repos/fabric-p4.yaml
+++ b/jjb/repos/fabric-p4.yaml
@@ -31,7 +31,7 @@
 
     jobs:
       - 'verify-fabric-p4-jobs':
-          branch-regexp: '2.*'
+          branch-regexp: 'onos-2.*'
           stream: 'master'
 
 - job-group: