Revert "Revert "qcom-common: Add RIL startup script for IPv6 tethering""

This reverts commit 163127d2c1e45ac80c213224f3ee1fd9d6f7418f.
Revert "Revert "qcom-common: add common qcom ril class""

This reverts commit d5f888994cfce55bf4068a53233daebdc2a73b32.