[ot] hw/opentitan: ot_rom_ctrl: implement local address scrambling and ECC

This should enable support for loading ELF, binary and plain text VMEM files
as ROM image file while preserving proper KeyManager DPE computations,
which is expected to be performed on scrambled address & ECC ROM content.

Signed-off-by: Emmanuel Blot <[email protected]>

Author: rivos-eblot