wifi: rtw89: phy: add dummy C2H handler to avoid warning message

The C2H class 2 function 3 is to report retry count of low rate, but driver
doesn't implement yet, so add a dummy case to avoid message:

  rtw89_8852be 0000:03:00.0: c2h class 2 not support

Signed-off-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20221014060237.29050-4-pkshih@realtek.com