Support for MPC5643L.

Rework of the start sequence to reduce the amount assembler code and to
support configuration tables which may be provided by the application.

c/src/lib/libcpu/powerpc/new-exceptions/bspsupport/ppc_exc_categories.c

@@ -274,6 +274,7 @@ const ppc_exc_categories *ppc_exc_categories_for_cpu(ppc_cpu_id_t cpu)
       return &e500_category_table;
     case PPC_e200z0:
     case PPC_e200z1:
+    case PPC_e200z4:
     case PPC_e200z6:
     case PPC_e200z7:
       return &e200_category_table;