[dv] Fix compile warning  in cip_base_scoreboard
[dv] Fix compile warning  in cip_base_scoreboard

- This fixes a warning thrown in `cip_base_scoreboard` related to the
instantiation of a `mem_model` instance.

Signed-off-by: Srikrishna Iyer <2803d640feace36379942447842f26c7747b4dc3@google.com>

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