patch 8.0.0466: still macros that should be all-caps

Problem:    There are still a few macros that should be all-caps.
Solution:   Make a few more macros all-caps.
diff --git a/src/ops.c b/src/ops.c
index d3e97f0..9cff1bc 100644
--- a/src/ops.c
+++ b/src/ops.c
@@ -4112,7 +4112,7 @@
 
     if (arg != NULL && *arg == NUL)
 	arg = NULL;
-    attr = hl_attr(HLF_8);
+    attr = HL_ATTR(HLF_8);
 
     /* Highlight title */
     MSG_PUTS_TITLE(_("\n--- Registers ---"));