staging: gdm72xx: use int instead of u32 whenever makes sense

This patch addresses the following issues:
- Use int instead of u32 whenever makes sense
- Turn extract_qos_list() in gdm_qos.c, which previously always returned
  0, into a void function.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reported-by: Michalis Pappas <mpappas@fastmail.fm>
Signed-off-by: Ben Chan <benchan@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>