[dv/otp_ctrl] Add back ECC correctable coverage bin
[dv/otp_ctrl] Add back ECC correctable coverage bin

This PR fixes a previous TODO by adding back the ECC correctable
coverbin.

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

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