wifi: mt76: mt7996: fix unintended sign extension of mt7996_hw_queue_read()

In the expression "map[i].qid << 24" starts as u8, but is promoted to
"signed int", then sign-extended to type "unsigned long", which is not
intended. Cast to u32 to avoid the sign extension.

Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
Addresses-Coverity-ID: 1527813 ("Integer handling issues")
Fixes: 98686cd2 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>