[dv/lc_ctrl] Add tb.svg to lc_ctrl dv doc
[dv/lc_ctrl] Add tb.svg to lc_ctrl dv doc

This PR adds the tb.svg diagram for lc_ctrl dv plan.

Signed-off-by: Cindy Chen <399ad771a111eac8923348b1e2af093034e5d4f1@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan