Remove useless Result import (#3534)

Latest Rust nightly complains with `the item `Result` is imported
redundantly`

Co-authored-by: Sebastian Kunert <skunert49@gmail.com>
Co-authored-by: Liam Aharon <liam.aharon@hotmail.com>

substrate/primitives/consensus/babe/src/inherents.rs

@@ -17,7 +17,6 @@
 
 //! Inherents for BABE
 
-use core::result::Result;
 use sp_inherents::{Error, InherentData, InherentIdentifier};
 
 /// The BABE inherent identifier.