patch 8.2.5107: some callers of rettv_list_alloc() check for not OK

Problem:    Some callers of rettv_list_alloc() check for not OK. (Christ van
            Willegen)
Solution:   Use "==" instead of "!=" when checking the return value.
diff --git a/src/term.c b/src/term.c
index 9e26eab..c40f9f5 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1470,7 +1470,7 @@
     int i;
 # endif
 
-    if (rettv_dict_alloc(rettv) != OK)
+    if (rettv_dict_alloc(rettv) == FAIL)
 	return;
 # ifdef FEAT_TERMRESPONSE
     for (i = 0; i < TPR_COUNT; ++i)