luci-app-voice-core and -diag: mark broken

Mark luci-app-voice-core and luci-app-voice-diag @BROKEN as their only functionality
is to create menu structure to be filled by items from luci-app-diag-devinfo,
which is currently broken due to missing dependencies.

References:

Initial commit creating all three packages:
https://github.com/openwrt/luci/commit/820f1193

Explanation why luci-app-diag-devinfo is currently broken:
https://github.com/openwrt/luci/commit/ec6ccf1c



If luci-app-diag-devinfo gets its dependencies fixed, these two voice packages
might be re-activated. Combining the three packages would increase clarity.

Signed-off-by: Hannu Nyman <hannu.nyman@iki.fi>