[prim/secded] Find optimal Fan-In
[prim/secded] Find optimal Fan-In

The SECDED generator is revised to find the optimal fan-in logic.
Current one uses random shuffle to find the parity matrix that meets the
ideal fan-in value.

Later, it would be useful to find the deterministically such as choosing
the row that doesn't violate the ideal fan-in one-by-one.

Signed-off-by: Eunchan Kim <cb7bc7ceb22698f298c67faa994fd9ddf3cab298@opentitan.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan