rtw88: notify fw when driver in scan-period to avoid potential problem

It is found that driver scan could be affected by dynamic mechanism
of firmware, so we notify firmware to stop it in the scan period.
Another, firmware will detect the background noise and report to
driver for further use.

Signed-off-by: Chin-Yen Lee <timlee@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210514075517.14216-3-pkshih@realtek.com