scsi: core: Rename __scsi_error_from_host_byte() into scsi_result_to_blk_status()

Since the next patch will modify this function such that it checks more than
just the host byte of the SCSI result, rename __scsi_error_from_host_byte()
into scsi_result_to_blk_status().  This patch does not change any
functionality.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Lee Duncan <lduncan@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>