wifi: rtw89: fix power save function in WoWLAN mode

In WoWLAN Mode, it's expected that WiFi chip could enter power save mode
only after all setting is finished, but current wow_enter_lps function
break the rule and may lead to WoWLAN function fail in low probability,
so fix it.

Signed-off-by: Chih-Kang Chang <gary.chang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230410053438.10682-2-pkshih@realtek.com