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];
          |            ^~~~

0 files changed, 0 insertions, 0 deletions