[otp_ctrl,dv] The mem backdoor needs parameterising for different top-levels

[rswarbrick]

Description

At the moment, we include a bunch of code into mem_bkdr_util.sv, including mem_bkdr_util__otp.svh. That includes a function with the following prototype:

virtual function void otp_write_hw_cfg1_partition(
    bit [EnCsrngSwAppReadSize*8-1:0] en_csrng_sw_app_read,
    bit [EnSramIfetchSize*8-1:0] en_sram_ifetch,
    bit [EnSramIfetchSize*8-1:0] dis_rv_dm_late_debug);
  bit [HwCfg1DigestSize*8-1:0] digest;

Unfortunately, EnCsrngSwAppReadSize is now generated as part of the ipgen flow for otp_ctrl and that parameter is not available to mem_bkdr_util.sv.

As a short-term hack, we can replace that with the value we used in EarlGrey (which is 1). Longer term, we should probably "do this properly". Maybe a nice solution would be to define a subclass of mem_bkdr_util for each top-level, and define this sort of top-level-specific function there.

[vogelpi]

Thanks for creating the issue Rupert. This is related to #25891 (which tracks the more generic issue of specialized code that needs to be moved out of mem backdoor).