blk_end_request: changing sx8 (take 4)

blk_end_request: changing sx8 (take 4)

This patch converts sx8 to use blk_end_request interfaces.
Related 'uptodate' and 'is_ok' arguments are converted to 'error'.

As a result, the interfaces of internal functions below are changed.
  o carm_end_request_queued
  o carm_end_rq
  o carm_handle_array_info
  o carm_handle_scan_chan
  o carm_handle_generic
  o carm_handle_rw

The 'is_ok' is set at only one place in carm_handle_resp() below:

	int is_ok = (status == RMSG_OK);

And the value is propagated to all functions above, and no modification
in other places.
So the actual conversion of the 'is_ok' is done at only one place above.

Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Kiyoshi Ueda <k-ueda@ct.jp.nec.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>