ACPI / memhotplug: set info->enabled for memory present at boot time

At http://marc.info/?l=linux-acpi&m=135769405622667&w=2 thread,
Toshi Kani mentioned as follows:

"I have a question about the change you made in commit 65479472 in
acpi_memhotplug.c.  This change seems to require that
acpi_memory_enable_device() calls add_memory() to add all memory ranges
represented by memory device objects at boot-time, and keep the results
be used for hot-remove.

If I understand it right, this add_memory() call fails with EEXIST at
boot-time since all memory ranges should have been added from EFI memory
table (or e820) already.  This results all memory ranges be marked as !
enabled & !failed.  I think this means that we cannot hot-delete any
memory ranges presented at boot-time since acpi_memory_remove_memory()
only calls remove_memory() when the enabled flag is set.  Is that
correct?"

Above mention is correct. Thus even if memory device supports hotplug,
memory presented at boot-time cannot be hot removed since the memory
device's acpi_memory_info->enabled is always 0.

This patch changes to set 1 to "acpi_memory_info->enabled" of memory
device presented at boot-time for hot removing the memory device.
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_memhotplug.c

@@ -206,8 +206,8 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 			continue;
 		}
 
-		if (!result)
-			info->enabled = 1;
+		info->enabled = 1;
+
 		/*
 		 * Add num_enable even if add_memory() returns -EEXIST, so the
 		 * device is bound to this driver.