bugfix missing byte swap for the create2 salt value (#272)

Found in https://github.com/paritytech/contract-issues/issues/45, thanks
@albertov19 and @sekisamu

---------

Signed-off-by: xermicus <cyrill@parity.io>
Signed-off-by: Cyrill Leutwiler <bigcyrill@hotmail.com>

crates/llvm-context/src/polkavm/evm/create.rs

@@ -32,6 +32,7 @@ where
     let salt_pointer = match salt {
         Some(salt) => {
             let salt_pointer = context.build_alloca_at_entry(context.word_type(), "salt_pointer");
+            let salt = context.build_byte_swap(salt.into())?;
             context.build_store(salt_pointer, salt)?;
             salt_pointer
         }