acpi_memhotplug.c: remove memory info from list before freeing it

acpi_memhotplug.c: remove memory info from list before freeing it

We free info, but we forget to remove it from the list.  It will cause
unexpected problems when we access the list next time.

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>