[][mt7986: Correct emmc target image name]

[Description]
Fix emmc image name.

[Release-log]
N/A

Change-Id: Ie864a339a42017bb65e67e3bd35a27cc905eabb2
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/4977996
1 file changed