Revert some changes to address comments

Author: c410-f3r

core/sr-primitives/src/sr_arithmetic.rs

@@ -20,7 +20,7 @@
 use crate::serde::{Serialize, Deserialize};
 
 use rstd::{
-	ops, ops::Div, cmp::Ordering, prelude::*,
+	ops, cmp::Ordering, prelude::*,
 	convert::{TryFrom, TryInto},
 };
 use codec::{Encode, Decode};
@@ -178,7 +178,7 @@ macro_rules! implement_per_thing {
 					// `rem_multiplied_upper` is less than $max^2 therefore divided by $max it fits
 					// in $type. remember that $type always fits $max.
 					let mut rem_multiplied_divided_sized =
-						rem_multiplied_upper.div(upper_max) as $type;
+						(rem_multiplied_upper / upper_max) as $type;
 					// fix a tiny rounding error
 					if rem_multiplied_upper % upper_max > upper_max / 2 {
 						rem_multiplied_divided_sized += 1;

core/sr-primitives/src/traits.rs

@@ -475,7 +475,7 @@ pub trait Hash: 'static + MaybeSerializeDebug + Clone + Eq + PartialEq {
 #[cfg_attr(feature = "std", derive(Debug, Serialize, Deserialize))]
 pub struct BlakeTwo256;
 
-impl self::Hash for BlakeTwo256 {
+impl Hash for BlakeTwo256 {
 	type Output = primitives::H256;
 	type Hasher = Blake2Hasher;