acpi_memhotplug.c: bind the memory device when the driver is being loaded

acpi_memhotplug.c: bind the memory device when the driver is being loaded

We had introduced acpi_hotmem_initialized to avoid strange add_memory fail
message.  But the memory device may not be used by the kernel, and the
device should be bound when the driver is being loaded.  Remove
acpi_hotmem_initialized to allow that the device can be bound when the
driver is being loaded.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: Len Brown <lenb@kernel.org>
Cc: "Brown, Len" <len.brown@intel.com>
Cc: Yasuaki ISIMATU <isimatu.yasuaki@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>