wifi: mt76: mt7996: fix rate usage of inband discovery frames

wifi: mt76: mt7996: fix rate usage of inband discovery frames

[ Upstream commit 1e3f387736c744e73b5398a147b90412f82f54da ]

For UBPR and FILS frames, the BSS_CHANGED_BEACON flag will also be set,
which causes those frames to use the beacon rate in TX descriptors.
Adjust the statement to fix this issue.

Fixes: 98686cd21624 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Signed-off-by: MeiChia Chiu <meichia.chiu@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Sasha Levin <sashal@kernel.org>