Update version for v8.0.0-rc2 release

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/VERSION b/VERSION
index 2b20514..3675c3c 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-7.2.91
+7.2.92