Add and use rtems_blkdev_request_done(). Block device transfer requests
must signal the completion status now with rtems_blkdev_request_done().
The return value of the block device IO control will be ignored for
transfer requests.
The first parameter of rtems_blkdev_request_cb is now the transfer
request structure.
Renamed rtems_blkdev_request::req_done to rtems_blkdev_request::done to
break third party drivers at compile time, otherwise this API change
would result in runtime errors.
The functions
o rtems_bdbuf_get(),
o rtems_bdbuf_read(),
o rtems_bdbuf_syncdev(), and
o rtems_bdbuf_purge_dev(),
use now the disk device instead of the device identifier. This makes
bdbuf independent of rtems_disk_obtain() and rtems_disk_release(). It
is the responsiblity of the file system to obtain the disk device. This
also reduces the overhead to get a buffer.
The key for the AVL tree uses now the disk device instead of the device
identifier. The pointer is interpreted as an unsigned integer. This
reduces the memory overhead and makes the comparison operation a bit
faster.
Removed function rtems_bdbuf_purge_major(). This function was too
destructive and could have unpredictable side effects.
