mt76: move MT_TXD_INFO, MT_MCU_MSG and MT_RX_FCE_INFO defs in dma.h

Since MT_TXD_INFO, MT_MCU_MSG and MT_RX_FCE_INFO definitions are in
common between mt76x2u, mt76x2 and mt76x0u move them in dma.h in order
to reuse usb code supporting mt76x2u and mt76x0u based devices

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>