mt76: mt7615: fix NULL pointer dereference in tx_prepare_skb()
Fix theoretical NULL pointer dereference in mt7615_tx_prepare_skb and
mt7663_usb_sdio_tx_prepare_skb routines. This issue has been identified
by code analysis.
Fixes: e51e8d2e781e7 ("mt76: mt7615: implement DMA support for MT7622") Fixes: 8b5095c14de0f ("mt76: mt7663u: sync probe sampling with rate configuration") Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org> Signed-off-by: Felix Fietkau <nbd@nbd.name>