remove unnecessary pair of parens

Author: benschulz

tests/ui/traits/impl-2.rs

@@ -10,7 +10,7 @@ pub mod Foo {
 }
 
 mod Bar {
-    impl<'a> dyn (crate::Foo::Trait) + 'a {
+    impl<'a> dyn crate::Foo::Trait + 'a {
         fn bar(&self) { self.foo() }
     }
 }