wifi: rtw89: coex: Enable Wi-Fi RX gain control for free run solution

When Wi-Fi & Bluetooth are both busy at the same time, Wi-Fi need to
enable RX gain to protect Wi-Fi RX RF ability. Without this configure
the interference from Bluetooth will bring a big impact to Wi-Fi RX.

Signed-off-by: Ching-Te Ku <ku920601@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/20230412012831.10519-2-pkshih@realtek.com