rtlwifi: Replace hardcode value with macro

In _rtl_init_mac80211(), hardcoded value for hw->max_listen_interval
and hw->max_rate_tries are replaced by macro and removed the comment.

Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
Acked-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>