mt76: usb: move mt76u_skb_dma_info in mt76x02_usb_core.c

mt76: usb: move mt76u_skb_dma_info in mt76x02_usb_core.c

Move mt76u_skb_dma_info routine in mt76x02-usb module and rename it in
mt76x02u_skb_dma_info. Moreover move mt76x02u_set_txinfo in
mt76x02_usb_core.c. This is a preliminary patch to move MT_TXD_INFO,
MT_MCU_MSG and MT_RX_FCE_INFO defs in mt76x02-lib module since other
chipsets (e.g. mt7603) use different dma definitions

Acked-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>