lima: disasm: use last argument as a filename

Otherwise it fails to open a file.

Fixes: 9660427ab7 ("lima: Print usage if --help is any of the arguments.")
Reviewed-by: Andreas Baierl <ichgeh@imkreisrum.de>
Signed-off-by: Vasily Khoruzhick <anarsoul@gmail.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13968>

src/gallium/drivers/lima/standalone/lima_disasm.c

@@ -166,7 +166,7 @@ main(int argc, char **argv)
    }
 
    char *filename = NULL;
-   filename = argv[n];
+   filename = argv[argc - 1];
 
    uint32_t size = 0;
    uint32_t *prog = extract_shader_binary(filename, &size, &is_frag);