arch: arm: be able to infer Z_ARCH_EXCEPT() for baseline SOCs

This commit makes it possible to infer Z_ARCH_EXCEPT()
calls in SVCs that escalate to HardFault due to being
invoked from priority level equal or higher to the
interrupt priority level of the SVC Handler.

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