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/crypto/dllmain.c b/crypto/dllmain.c
index b0459c2..81bcb2d 100644
--- a/crypto/dllmain.c
+++ b/crypto/dllmain.c
@@ -55,7 +55,7 @@
     case DLL_PROCESS_DETACH:
         break;
     }
-    return (TRUE);
+    return TRUE;
 }
 #endif