wifi: rtw89: correct header conversion rule for MLO only

Header conversion should only be used with MLO connections. Otherwise
P2P connection fails due to wrong probe responses sent. Fix it
accordingly.

Fixes: b8499664 ("wifi: rtw89: Add header conversion for MLO connections")
Signed-off-by: Po-Hao Huang <phhuang@realtek.com>
Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Link: https://patch.msgid.link/20241231004811.8646-4-pkshih@realtek.com