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/channel.c b/src/channel.c
index abd2ce1..8a64d17 100644
--- a/src/channel.c
+++ b/src/channel.c
@@ -5275,7 +5275,7 @@
 	return;
 
     channel = get_channel_arg(&argvars[0], FALSE, FALSE, 0);
-    if (channel != NULL && rettv_dict_alloc(rettv) != FAIL)
+    if (channel != NULL && rettv_dict_alloc(rettv) == OK)
 	channel_info(channel, rettv->vval.v_dict);
 }