src/plugins/callbacks.c: drop redundant NULL pointer check

gcc-12 detects redundant check against array of arrays as:

    src/plugins/callbacks.c: In function ‘_free_command_help’:
    src/plugins/callbacks.c:85:26: error: the comparison will always evaluate as ‘true’ for the address of ‘args’ will never be NULL [-Werror=address]
       85 |     while (help->args[i] != NULL && help->args[i][0] != NULL) {
          |                          ^~
    In file included from ./src/ui/ui.h:44,
                     from ./src/command/cmd_defs.h:42,
                     from src/plugins/callbacks.c:41:
    ./src/command/cmd_funcs.h:48:12: note: ‘args’ declared here
       48 |     gchar* args[128][2];
          |            ^~~~

1 files changed, 1 insertions, 1 deletions

diff --git a/src/plugins/callbacks.c b/src/plugins/callbacks.c
index 92c0a9f4..4a73f15b 100644
--- a/src/plugins/callbacks.c
+++ b/src/plugins/callbacks.c
@@ -82,7 +82,7 @@ _free_command_help(CommandHelp* help)
     free(help->desc);
 
     i = 0;
-    while (help->args[i] != NULL && help->args[i][0] != NULL) {
+    while (help->args[i][0] != NULL) {
         free(help->args[i][0]);
         free(help->args[i][1]);
         i++;