scripts/release-notes: Don't try to clone redbud-xml

The redbud platform uses the witherspoon-xml repository. There is no
redbud-xml repository so ignore it when creating a list of -xml
repositories.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
diff --git a/openpower/scripts/release-notes b/openpower/scripts/release-notes
index 4231aa0..da0bc6f 100755
--- a/openpower/scripts/release-notes
+++ b/openpower/scripts/release-notes
@@ -111,6 +111,7 @@
     next if $p =~ /firenze/;
     next if $p =~ /^zz$/;
     next if $p =~ /mambo/;
+    next if $p =~ /redbud/;
     $repos->{"$p-xml"} = { REPO => "http://github.com/open-power/$p-xml" ,
 			   DIR => "openpower/package/$p-xml" };
 }