eec94620 fold mg_disk.h into mg_disk.c,
but mg_disk platform driver needs private data for operation. This also
make mg_disk.c as machine independent. Seperate only needed structure and
defines to mg_disk.h
Signed-off-by: Nunsik Kim <donari75@gmail.com>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>