vmcore: modify vmcore clean-up function to free buffer on 2nd kernel

vmcore: modify vmcore clean-up function to free buffer on 2nd kernel

If flag MEM_TYPE_CURRENT_KERNEL is set, the object is copied in some
buffer on the 2nd kernel, so clean-up funciton needs to free it.

Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>