acpi_memhotplug.c: free memory device if acpi_memory_enable_device() failed

acpi_memhotplug.c: free memory device if acpi_memory_enable_device() failed

If acpi_memory_enable_device() fails, acpi_memory_enable_device() will
return a non-zero value, which means we fail to bind the memory device to
this driver.  So we should free memory device before
acpi_memory_device_add() returns.

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>