[][openwrt][common][audio][Remove obsolete mt79xx audio driver from module.mk]

[Description]
Remove obsolete mt79xx audio driver from module.mk which is replaced
with mt7986 audio driver.

[Release-log]
N/A

Change-Id: I42acea3f2edbb9d57218d053331397a319b4d28d
Reviewed-on: https://gerrit.mediatek.inc/c/openwrt/feeds/mtk_openwrt_feeds/+/8390031
1 file changed