No need to send both MCU_EXT_CMD_SET_RX_PATH and MCU_EXT_CMD_CHANNEL_SWITCH
together to MCU.

Split them out by passing the proper command in the corresponding flow.
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>