pc: Remove redundant code from pc-*-2.3 machine classes

Remove the redundant 'alias = NULL' and 'is_default = 0' lines
from older machine-types. pc_*_2_4_machine_options() already
clear those fields, so they don't need to be cleared by
pc_*_2_3_machine_options().
Reviewed-by: NMarcel Apfelbaum <marcel@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Reviewed-by: NThomas Huth <thuth@redhat.com>

hw/i386/pc_piix.c

@@ -448,8 +448,6 @@ static void pc_i440fx_2_3_machine_options(MachineClass *m)
 {
     pc_i440fx_2_4_machine_options(m);
     m->hw_version = "2.3.0";
-    m->alias = NULL;
-    m->is_default = 0;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_3);
 }
 

hw/i386/pc_q35.c

@@ -378,7 +378,6 @@ static void pc_q35_2_3_machine_options(MachineClass *m)
     m->hw_version = "2.3.0";
     m->no_floppy = 0;
     m->no_tco = 1;
-    m->alias = NULL;
     SET_MACHINE_COMPAT(m, PC_COMPAT_2_3);
 }