wifi: rtw89: refine leaving LPS function

It's unnecessary to iterate leaving PS mode.
So, move it out of the iteration.

Signed-off-by: Zong-Zhe Yang <kevin_yang@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/20220802123712.16577-1-pkshih@realtek.com