RT2560_TX_VALID
if ((flags & RT2560_TX_BUSY) || (flags & RT2560_TX_VALID) == 0)
desc->flags &= ~htole32(RT2560_TX_VALID);
desc->flags |= htole32(RT2560_TX_VALID);
desc->flags |= htole32(RT2560_TX_VALID);
!(flags & RT2560_TX_VALID))
desc->flags &= ~htole32(RT2560_TX_VALID);