[SCSI] use scmd_id(), scmd_channel() throughout code

Wrap a highly common idiom.  Makes the code easier to read, helps pave
the way for sdev->{id,channel} removal, and adds a token that can easily
by grepped-for in the future.

There are a couple sdev_id() and scmd_printk() updates thrown in as well.

Rejections fixed up and
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index add190e..aadf051 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -283,7 +283,7 @@
 	unsigned char *cmd = (unsigned char *) SCpnt->cmnd;
 	int block, upper_blk, num, k;
 	int errsts = 0;
-	int target = SCpnt->device->id;
+	int target = scmd_id(SCpnt);
 	struct sdebug_dev_info * devip = NULL;
 	int inj_recovered = 0;