Update lint deprecation for tool lints

Our lint deprecation previously didn't work for tool lints, because
`register_removed` was registering lints to be removed _without_ the
`clippy` prefix.

clippy_dev/src/lib.rs

@@ -126,7 +126,7 @@ pub fn gen_deprecated(lints: &[Lint]) -> Vec<String> {
             l.clone().deprecation.and_then(|depr_text| {
                 Some(vec![
                     "    store.register_removed(".to_string(),
-                    format!("        \"{}\",", l.name),
+                    format!("        \"clippy::{}\",", l.name),
                     format!("        \"{}\",", depr_text),
                     "    );".to_string(),
                 ])
@@ -442,11 +442,11 @@ fn test_gen_deprecated() {
     ];
     let expected: Vec<String> = vec![
         "    store.register_removed(",
-        "        \"should_assert_eq\",",
+        "        \"clippy::should_assert_eq\",",
         "        \"has been superseded by should_assert_eq2\",",
         "    );",
         "    store.register_removed(",
-        "        \"another_deprecated\",",
+        "        \"clippy::another_deprecated\",",
         "        \"will be removed\",",
         "    );",
     ]