hw/arm/vexpress: Check for CPU types in machine_run_board_init()

Leverage the common code introduced in commit c9cf636 ("machine:
Add a valid_cpu_types property") to check for the single valid CPU
type. Remove the now unused MachineClass::default_cpu_type field.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Gavin Shan <gshan@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20240129151828.59544-9-philmd@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/vexpress.c

@@ -783,22 +783,30 @@ static void vexpress_class_init(ObjectClass *oc, void *data)
 
 static void vexpress_a9_class_init(ObjectClass *oc, void *data)
 {
+    static const char * const valid_cpu_types[] = {
+        ARM_CPU_TYPE_NAME("cortex-a9"),
+        NULL
+    };
     MachineClass *mc = MACHINE_CLASS(oc);
     VexpressMachineClass *vmc = VEXPRESS_MACHINE_CLASS(oc);
 
     mc->desc = "ARM Versatile Express for Cortex-A9";
-    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a9");
+    mc->valid_cpu_types = valid_cpu_types;
 
     vmc->daughterboard = &a9_daughterboard;
 }
 
 static void vexpress_a15_class_init(ObjectClass *oc, void *data)
 {
+    static const char * const valid_cpu_types[] = {
+        ARM_CPU_TYPE_NAME("cortex-a15"),
+        NULL
+    };
     MachineClass *mc = MACHINE_CLASS(oc);
     VexpressMachineClass *vmc = VEXPRESS_MACHINE_CLASS(oc);
 
     mc->desc = "ARM Versatile Express for Cortex-A15";
-    mc->default_cpu_type = ARM_CPU_TYPE_NAME("cortex-a15");
+    mc->valid_cpu_types = valid_cpu_types;
 
     vmc->daughterboard = &a15_daughterboard;