wifi: mt76: mt7996: fix RX buffer size of MCU event

[ Upstream commit 42cb27af ]

Some management frames are first processed by the firmware and then
passed to the driver through the MCU event rings. In CONNAC3, event rings
do not support scatter-gather and have a size limitation of 2048 bytes.
If a packet sized between 1728 and 2048 bytes arrives from an event ring,
the ring will hang because the driver attempts to use scatter-gather to
process it.

To fix this, include the size of struct skb_shared_info in the MCU RX
buffer size to prevent scatter-gather from being used for event skb in
mt76_dma_rx_fill_buf().

Fixes: 98686cd2 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Co-developed-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Peter Chiu <chui-hao.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Link: https://patch.msgid.link/20250515032952.1653494-7-shayne.chen@mediatek.com


Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>