Unaligned read to Safety Island SPM fails

[bluewww]

A unaligned read from CVA6 to any address should result in an load exception.

Currently, a double word load to CAR_SAFETY_ISLAND_SPM_BASE_ADDR + 1 causes the core to lock up.

[alex96295]

@micprog coud you please have a look at this? To assess the claim and fix it, in case.

Test was added to PR #91 (needs a rebase)

[alex96295]

@micprog since we were talking about tests; this is maybe something to investigate (also post TO), because it can be a test failure or a HW bug