Revert "Allow a false-positive clippy lint"

The issue has been fixed with the latest clippy release and we don't
have to `allow` anymore.

This reverts commit 7f990144cc.

src/format/mod.rs

@@ -269,8 +269,6 @@ macro_rules! fix  { ($x:ident) => (Item::Fixed(Fixed::$x)) }
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
 pub struct ParseError(ParseErrorKind);
 
-// clippy false positive https://github.com/rust-lang-nursery/rust-clippy/issues/2475
-#[cfg_attr(feature = "cargo-clippy", allow(empty_line_after_outer_attr))]
 #[derive(Debug, Clone, PartialEq, Eq, Copy)]
 enum ParseErrorKind {
     /// Given field is out of permitted range.