[SCSI] constants.c: cleanup, verbose result printing

Clean up constants.c and make result printing more user friendly:

 - Refactor the command and sense functions so that the actual
   formatting can be called from the various helper functions with the
   correct prefix.

 - Replace scsi_print_hostbyte() and scsi_print_driverbyte() with
   scsi_print_result() which is verbose when CONFIG_SCSI_CONSTANTS is
   on.

Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>