remove fixme comment

Author: josetorrs

compiler/rustc_hir/src/hir.rs

@@ -3344,8 +3344,6 @@ pub enum TraitFn<'hir> {
 /// Represents a trait method or associated constant or type
 #[derive(Debug, Clone, Copy, StableHash)]
 pub enum TraitItemKind<'hir> {
-    // FIXME(mgca) eventually want to move the option that is around `ConstItemRhs<'hir>`
-    // into `ConstItemRhs`, much like `ast::ConstItemRhsKind`
     /// An associated constant with an optional value (otherwise `impl`s must contain a value).
     Const(&'hir Ty<'hir>, Option<ConstItemRhs<'hir>>),
     /// An associated function with an optional body.