Revert "3G modem support (from branch tomato-shibby)"

This reverts commit 7666fe7d6c383530054c1462a8a587d8b700ae5f.
Revert "Allow turn on/off sd-idle via GUI"

This reverts commit 9f1e8606dba9a4c8e276f2b898543241084462ec.
Revert "add sd-idle tool for K2.6"

This reverts commit 3f20ed6cdf499b719f792157b8082a2509bb9d9e.