release-notes: Update to account for single witherspoon platform

The release-notes script gets confused by the existence of both
witherspoon_sequoia_defconfig and witherspoon_defconfig. In this
scenario witherspoon_sequoia_defconfig only exists to placate the CI
process, so treat it as if it does not exist.

Signed-off-by: Samuel Mendoza-Jonas <sam@mendozajonas.com>
diff --git a/openpower/scripts/release-notes b/openpower/scripts/release-notes
index a0f322f..33974d5 100755
--- a/openpower/scripts/release-notes
+++ b/openpower/scripts/release-notes
@@ -74,6 +74,23 @@
 
 my $witherspoon_insanity;
 
+# If both witherspoon and witherspoon-sequoia exist we've switched back
+# to a single witherspoon platform and the -sequoia platform is just to
+# keep Jenkins happy - ignore it.
+if ("witherspoon" ~~ @begin_platforms
+	&& "witherspoon-sequoia" ~~ @begin_platforms) {
+	my $index = 0;
+	$index++ until @begin_platforms[$index] eq "witherspoon-sequoia";
+	splice(@begin_platforms, $index, 1);
+}
+
+if ("witherspoon" ~~ @end_platforms
+	&& "witherspoon-sequoia" ~~ @end_platforms) {
+	my $index = 0;
+	$index++ until @end_platforms[$index] eq "witherspoon-sequoia";
+	splice(@end_platforms, $index, 1);
+}
+
 if (($platform && $platform eq 'witherspoon')
     && -f "$end_worktree/openpower/configs/witherspoon-sequoia_defconfig") {
     @begin_platforms = ('witherspoon');