.asf.yaml: Disable squash and merge option

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
diff --git a/.asf.yaml b/.asf.yaml
index 80ae5c2..9e05828 100644
--- a/.asf.yaml
+++ b/.asf.yaml
@@ -15,9 +15,9 @@
     - microcontroller
     - ci
   enabled_merge_buttons:
-    # enable squash button:
-    squash:  true
-    # enable merge button:
-    merge:   true
+    # disable squash button:
+    squash:  false
+    # disable merge button:
+    merge:   false
     # enable rebase button:
     rebase:  true