[fpga,english_breakfast] english_breakfast CW305 bitstream build broken due to missing Boot ROM BRAM implementation

### Description

See the error logs in the monthly build job [here](https://github.com/lowRISC/opentitan/actions/runs/28482445882/job/84421590346#step:4:5623).

I'm not sure if it is a change to the `rom_ctrl`, the boot ROM itself or the BRAM mapping / MMI file generation that has caused the issue, but the relevant error is:
```
opt_design: Time (s): cpu = 00:01:25 ; elapsed = 00:01:00 . Memory (MB): peak = 3911.879 ; gain = 902.113 ; free physical = 9319 ; free virtual = 45215
source /home/runner/.cache/bazel/_bazel_runner/009b5905a925a435539a99f3bc28ac3e/sandbox/processwrapper-sandbox/1/execroot/_main/bazel-out/k8-fastbuild/bin/hw/top_englishbreakfast/bitstream/build.fpga_cw305/lowrisc_systems_chip_englishbreakfast_cw305_0.1/synth-vivado/vivado_hook_opt_design_post.tcl
INFO: [Designcheck 2-1] Checking if Boot ROM is mapped to BRAM.
WARNING: [Vivado 12-180] No cells matched 'get_cells -hierarchical -filter { NAME =~ "*u_rom_ctrl*u_rom*u_prim_rom*" && PRIMITIVE_TYPE =~ BMEM.*.* }'.
ERROR: [Designcheck 2-3] BRAM implementation not found for Boot ROM.
ERROR: [Common 17-39] 'send_msg_id' failed due to earlier errors.
sourcing script /home/runner/.cache/bazel/_bazel_runner/009b5905a925a435539a99f3bc28ac3e/sandbox/processwrapper-sandbox/1/execroot/_main/bazel-out/k8-fastbuild/bin/hw/top_englishbreakfast/bitstream/build.fpga_cw305/lowrisc_systems_chip_englishbreakfast_cw305_0.1/synth-vivado/vivado_hook_opt_design_post.tcl failed
INFO: [Common 17-206] Exiting Vivado at Tue Jun 30 23:42:41 2026...
```

Start with the linked monthly build job and the hw/top_englishbreakfast/bitstream Vivado logs, then inspect rom_ctrl, the boot ROM, and the BRAM mapping/MMI file generation mentioned in the issue. Trace why the post-opt_design check cannot find the expected Boot ROM BRAM cells. Done means the english_breakfast CW305 bitstream build completes with the BRAM implementation detected.

Written by the indexing model from the issue text.