scsi: increase upper limit for max_sectors

max_sectors in struct Scsi_Host specifies maximum number of sectors
allowed in a single SCSI command.  The data type of max_sectors is
unsigned short, so the maximum transfer length per SCSI command is
limited to less than 256MB in 4096-bytes sector size. (0xffff * 4096)

This commit increases the SCSI mid level's limitation for max_sectors
upto the block layer's limitation for max_hw_sectors by extending the
data type of max_sectors in struct Scsi_Host and scsi_host_template,
so that SCSI lower level drivers can specify more than 0xffff.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

include/scsi/scsi_host.h

@@ -408,7 +408,7 @@ struct scsi_host_template {
 	/*
 	 * Set this if the host adapter has limitations beside segment count.
 	 */
-	unsigned short max_sectors;
+	unsigned int max_sectors;
 
 	/*
 	 * DMA scatter gather segment boundary limit. A segment crossing this
@@ -652,7 +652,7 @@ struct Scsi_Host {
 	short cmd_per_lun;
 	short unsigned int sg_tablesize;
 	short unsigned int sg_prot_tablesize;
-	short unsigned int max_sectors;
+	unsigned int max_sectors;
 	unsigned long dma_boundary;
 	/* 
 	 * Used to assign serial numbers to the cmds.