arch: arm: no HW stack protection capabilities in Cortex-M Baseline

We do not support HW Stack protection capabilities in
Cortex-M Baseline CPUs (unless they have built-in stack
overflow detection capability). We adapt the Kconfig
option to reflect this.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>