LU-1095 ptlrpc: improve ptlrpc debug message consistency

LU-1095 ptlrpc: improve ptlrpc debug message consistency

Enforce the following conventions for better consistency
in a few ptlrpc/target.c debug messages.

- Print each message on a single line for better grep results.

- Provide a distinctive message for different functions to
  reduce appearance of redundancy.

- Print device name at the start, otherwise on systems with many
  targets it isn't easy to tell which one was involved.

- Print rc at the end.

Signed-off-by: Ned Bass <bass6@llnl.gov>
Change-Id: Ibd203367dde4d95d32671217271420c57a8dc0ad
Reviewed-on: http://review.whamcloud.com/3547
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>