wifi: rtw89: remove redundant check of entering LPS

Originally, add this check rule to prevent entering LPS if more than one
vif (in station mode) connect to AP. Since we have checked this by previous
commit, remove this redundant check.

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230527082939.11206-4-pkshih@realtek.com