Remove unnecessary write_all impl

zebra-chain/src/sha256d_writer.rs

@@ -27,17 +27,6 @@ impl Write for Sha256dWriter {
         Ok(buf.len())
     }
 
-    fn write_all(&mut self, buf: &[u8]) -> std::io::Result<()> {
-        let mut length = 0;
-
-        while length != buf.len() {
-            length += buf.len();
-            self.hash.input(buf);
-        }
-
-        Ok(())
-    }
-
     fn flush(&mut self) -> std::io::Result<()> {
         Ok(())
     }