[otp_ctrl] Increase Hamming distance in OTP commands

[msfschaffner]

This a security patch for closing out D2S for OTP_CTRL.

Fixes #21948

[msfschaffner]

@arnonsha @meisnere @sha-ron FYI

This is a security patch that touches the primitive wrapper interface.
We will have to update the encoding in the closed source wrapper once you ingest a newer M2 release candidate than RC0.

[matutem]

I thought we typically aimed for higher hamming distances?

[msfschaffner]

For FSM encodings, yes, we would typically do 4 or 5, but at least 3.
I am not sure this is really required in this setting for the command.
We can do 4, but the command needs to be 7bit wide then for this to work.

[msfschaffner]

I increased the HD to 4

[andreaskurth]

LGTM, thanks!

[vogelpi]

LGTM, thanks @msfschaffner !

In case you need to push once more, there is also a comment in hw/ip/prim_generic/rtl/prim_generic_otp.sv mentioning the now outdated 3-bit commands.

For refernce, commit dc9da97 added the raw commands ignoring the integrity.

[msfschaffner]

In case you need to push once more, there is also a comment in hw/ip/prim_generic/rtl/prim_generic_otp.sv mentioning the now outdated 3-bit commands.

I patched that up, thanks!