wifi: rtw89: scan abort when assign/unassign_vif

If scan happen during start_ap, the register which control TX might be
turned off during scan. Additionally, if set_channel occurs during scan
will backup this register and set to firmware after set_channel done.
When scan complete, firmware will also set TX by this register, causing
TX to be disabled and beacon can't be TX. Therefore, in assign/unassign_vif
call scan abort before set_channel to avoid scan racing with set_channel.

Signed-off-by: Chih-Kang Chang <gary.chang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20250610130034.14692-13-pkshih@realtek.com