userid-validation: add Plexus to approved companies

CLA has been submitted and uploaded to google drive

Change-Id: Ic5ea03aa9373ce1479e62a464bc06f7fb1adde33
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/jenkins/userid-validation b/jenkins/userid-validation
index c24af83..97938f2 100755
--- a/jenkins/userid-validation
+++ b/jenkins/userid-validation
@@ -97,6 +97,7 @@
         openbmc/ci-authorized \
         pcpartner/ci-authorized \
         phytium/ci-authorized \
+        plexus/ci-authorized \
         quanta/ci-authorized \
         quic/ci-authorized \
         rcs/ci-authorized \