rtlwifi: Correct power save capability while init mac80211

Since the driver itself will enter power saving mode dynamically
according to the traffic, we set hw capability SUPPORTS_PS and
SUPPORTS_DYNAMIC_PS in case of fwctrl_lps.

The process IEEE80211_CONF_CHANGE_PS in op_config is used by
SW-LPS only, so we add constraints to avoid errors.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: vincent_fann <vincent_fann@realtek.com>
Signed-off-by: shaofu <shaofu@realtek.com>
Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Yan-Hsuan Chuang <yhchuang@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>