scsi: rename SCSI_MAX_{SG, SG_CHAIN}_SEGMENTS

Rename SCSI_MAX_SG_SEGMENTS to SG_CHUNK_SIZE, which means the amount
we fit into a single scatterlist chunk.

Rename SCSI_MAX_SG_CHAIN_SEGMENTS to SG_MAX_SEGMENTS.

Will move these 2 generic definitions to scatterlist.h later.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Bart Van Assche <bart.vanassche@sandisk.com> (for ib_srp changes)
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/infiniband/ulp/srp/ib_srp.c

@@ -81,7 +81,7 @@ MODULE_PARM_DESC(cmd_sg_entries,
 
 module_param(indirect_sg_entries, uint, 0444);
 MODULE_PARM_DESC(indirect_sg_entries,
-		 "Default max number of gather/scatter entries (default is 12, max is " __stringify(SCSI_MAX_SG_CHAIN_SEGMENTS) ")");
+		 "Default max number of gather/scatter entries (default is 12, max is " __stringify(SG_MAX_SEGMENTS) ")");
 
 module_param(allow_ext_sg, bool, 0444);
 MODULE_PARM_DESC(allow_ext_sg,
@@ -3097,7 +3097,7 @@ static int srp_parse_options(const char *buf, struct srp_target_port *target)
 
 		case SRP_OPT_SG_TABLESIZE:
 			if (match_int(args, &token) || token < 1 ||
-					token > SCSI_MAX_SG_CHAIN_SEGMENTS) {
+					token > SG_MAX_SEGMENTS) {
 				pr_warn("bad max sg_tablesize parameter '%s'\n",
 					p);
 				goto out;