wifi: rtw89: leave idle mode when setting WEP encryption for AP mode

Due to mac80211 triggering the hardware to enter idle mode, it fails
to install WEP key causing connected station can't ping successfully.
Currently, it forces the hardware to leave idle mode before driver
adding WEP keys.

Signed-off-by: Dian-Syuan Yang <dian_syuan0116@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250507031203.8256-1-pkshih@realtek.com