wifi: mt76: mt7915: add dummy HW offload of IEEE 802.11 fragmentation

[ Upstream commit f2cc8591 ]

Currently, CONNAC2 series do not support encryption for fragmented Tx frames.
Therefore, add dummy function mt7915_set_frag_threshold() to prevent SW
IEEE 802.11 fragmentation.

Signed-off-by: Benjamin Lin <benjamin-jw.lin@mediatek.com>
Link: https://patch.msgid.link/20240827093011.18621-16-nbd@nbd.name


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