[SCSI] libosd: SCSI/OSD Sense decoding support

Implementation of the osd_req_decode_sense() API. Can be called by
library users to decode what failed in command executions.

Add SCSI_OSD_DPRINT_SENSE Kconfig variable. Possible values are:
0 - Do not print any errors to messages file <KERN_ERR>
1 - (Default) Print only decoded errors that are not recoverable.
    Recoverable errors are those that the target has complied with
    the request but with a warning. For example read passed end of
    object will return zeros after the last valid byte.
2- Print all errors.

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>