Bump test coverage value for x86_64

The last commit adds tests, that cover all of the default impls of functions,
causing the coverage to increase too much - bump the value manually.

Signed-off-by: Matej Hrica <[email protected]>

Author: mtjhrc

coverage_config_x86_64.json

@@ -1,5 +1,5 @@
 {
-  "coverage_score": 85.41,
+  "coverage_score": 86.22,
   "exclude_path": "vhost/src/vhost_kern/",
   "crate_features": "vhost/vhost-user-frontend,vhost/vhost-user-backend,vhost-user-backend/postcopy"
 }