hw: Do not initialize MachineClass::is_default to 0

The MachineClass is already zeroed on creation.

Note: The code setting is_default=0 in hw/i386/pc_piix.c is
      different (related to compat options). When adding a
      new versioned machine, we want it to be the new default,
      so we have to mark the previous one as not default.

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200207161948.15972-2-philmd@redhat.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

hw/lm32/lm32_boards.c

@@ -313,7 +313,6 @@ static void lm32_uclinux_class_init(ObjectClass *oc, void *data)
 
     mc->desc = "lm32 platform for uClinux and u-boot by Theobroma Systems";
     mc->init = lm32_uclinux_init;
-    mc->is_default = 0;
     mc->default_cpu_type = LM32_CPU_TYPE_NAME("lm32-full");
     mc->default_ram_size = 64 * MiB;
     mc->default_ram_id = "lm32_uclinux.sdram";

hw/lm32/milkymist.c

@@ -219,7 +219,6 @@ static void milkymist_machine_init(MachineClass *mc)
 {
     mc->desc = "Milkymist One";
     mc->init = milkymist_init;
-    mc->is_default = 0;
     mc->default_cpu_type = LM32_CPU_TYPE_NAME("lm32-full");
     mc->default_ram_size = 128 * MiB;
     mc->default_ram_id = "milkymist.sdram";

hw/m68k/q800.c

@@ -438,7 +438,6 @@ static void q800_machine_class_init(ObjectClass *oc, void *data)
     mc->init = q800_init;
     mc->default_cpu_type = M68K_CPU_TYPE_NAME("m68040");
     mc->max_cpus = 1;
-    mc->is_default = 0;
     mc->block_default_type = IF_SCSI;
     mc->default_ram_id = "m68k_mac.ram";
 }

hw/microblaze/petalogix_ml605_mmu.c

@@ -216,7 +216,6 @@ static void petalogix_ml605_machine_init(MachineClass *mc)
 {
     mc->desc = "PetaLogix linux refdesign for xilinx ml605 little endian";
     mc->init = petalogix_ml605_init;
-    mc->is_default = 0;
 }
 
 DEFINE_MACHINE("petalogix-ml605", petalogix_ml605_machine_init)

hw/tricore/tricore_testboard.c

@@ -105,7 +105,6 @@ static void ttb_machine_init(MachineClass *mc)
 {
     mc->desc = "a minimal TriCore board";
     mc->init = tricoreboard_init;
-    mc->is_default = 0;
     mc->default_cpu_type = TRICORE_CPU_TYPE_NAME("tc1796");
 }