wifi: mt76: mt7996: fix efuse reading issue

The efuse data starts from the 48th bytes instead of 64th bytes in the
returned event skb.

Fixes: 98686cd2

 ("wifi: mt76: mt7996: add driver for MediaTek Wi-Fi 7 (802.11be) devices")
Signed-off-by: StanleyYP Wang <StanleyYP.Wang@mediatek.com>
Signed-off-by: Shayne Chen <shayne.chen@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>