tests: kernel: smp: Test cpu affinity with custom ROM offset

What is the changed?
CPU affinity test for SMP cores will now cover a change in ROM offset.

How is it changed?
Add a new testcase section with ROM offset set to something other than
the default 0.

Why is it change?
There is no test to cover the issue reported in #76182 and the cpu
affinity test is the closest to test the issue. Adding a new testcase
will makes sure there is no breaking change in the future.

Signed-off-by: Sudan Landge <sudan.landge@arm.com>