wcn36xx: Remove unnecessary rcu_read_unlock in wcn36xx_bss_info_changed

No rcu_read_lock is called, but rcu_read_unlock is still called.
Thus rcu_read_unlock should be removed.

Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>