Remove parentheses of return.

Since return is inconsistent, I removed unnecessary parentheses and
unified them.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4541)
diff --git a/apps/errstr.c b/apps/errstr.c
index a02fa68..324e6e4 100644
--- a/apps/errstr.c
+++ b/apps/errstr.c
@@ -62,5 +62,5 @@
         }
     }
  end:
-    return (ret);
+    return ret;
 }