Update version for v8.0.0 release

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/VERSION b/VERSION
index 770b1c4..ae9a76b 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-7.2.94
+8.0.0