[pwrmgr,dv] Exercise all rom_ctrl inputs

https://github.com/lowRISC/opentitan/pull/25169 adds the ability to parametrize the number of rom_ctrl inputs. Earlgrey has 1 rom_ctrl but Darjeeling has 2.

While the aforementioned PR templates the number of rom_ctrl inputs in the RTL, the DV part only templates the minimum, i.e., the interface becomes an array. However DV does not yet exercise the other rom_ctrl inputs.

This issue is to track the effort to ipgen also the DV part to properly test rom_ctrls > 1.

/cc @andreaskurth @matutem

Start by reading PR #25169 and the issue’s description of the parametrized rom_ctrl inputs in RTL and DV. Trace the ipgen path for the DV interface, then ensure configurations with more than one rom_ctrl input are exercised; done means Darjeeling’s two inputs are properly tested.

Written by the indexing model from the issue text.