m68k/an5206: use memdev for RAM

memory_region_allocate_system_memory() API is going away, so
replace it with memdev allocated MemoryRegion. The later is
initialized by generic code, so board only needs to opt in
to memdev scheme by providing
  MachineClass::default_ram_id
and using MachineState::ram instead of manually initializing
RAM memory region.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200219160953.13771-47-imammedo@redhat.com>

hw/m68k/an5206.c

@@ -33,7 +33,6 @@ static void an5206_init(MachineState *machine)
     uint64_t elf_entry;
     hwaddr entry;
     MemoryRegion *address_space_mem = get_system_memory();
-    MemoryRegion *ram = g_new(MemoryRegion, 1);
     MemoryRegion *sram = g_new(MemoryRegion, 1);
 
     cpu = M68K_CPU(cpu_create(machine->cpu_type));
@@ -46,8 +45,7 @@ static void an5206_init(MachineState *machine)
     env->rambar0 = AN5206_RAMBAR_ADDR | 1;
 
     /* DRAM at address zero */
-    memory_region_allocate_system_memory(ram, NULL, "an5206.ram", ram_size);
-    memory_region_add_subregion(address_space_mem, 0, ram);
+    memory_region_add_subregion(address_space_mem, 0, machine->ram);
 
     /* Internal SRAM.  */
     memory_region_init_ram(sram, NULL, "an5206.sram", 512, &error_fatal);
@@ -89,6 +87,7 @@ static void an5206_machine_init(MachineClass *mc)
     mc->desc = "Arnewsh 5206";
     mc->init = an5206_init;
     mc->default_cpu_type = M68K_CPU_TYPE_NAME("m5206");
+    mc->default_ram_id = "an5206.ram";
 }
 
 DEFINE_MACHINE("an5206", an5206_machine_init)