[rom] ROM_EXT immutable section feature not compatible with address translation

[timothytrippel]

It has been pointed out that the ROM_EXT immutable section configuration did not account for the address translation adjustments to the immutable section entry point. This meant that if address translation was enabled, the immutable section entry point would never get moved to the virtual address space, which gets marked RX. The physical address space of the current slot would only be marked R, and when jumping to the entry point an exception would occur.

#24415 fixes the issue.