Despite this issue is not harmful since it is not actually used in
mt76 driver, fix DMA txinfo bitmask definition

Fixes: 7bc04215 ('mt76: add driver code for MT76x2e')
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>