[SCSI] 3w-xxxx: use sg buffer copy helper functions

This rewrites tw_transfer_internal with scsi_sg_copy_from/to_buffer.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Adam Radford <linuxraid@amcc.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

drivers/scsi/3w-xxxx.c

@@ -1463,18 +1463,10 @@ static void tw_transfer_internal(TW_Device_Extension *tw_dev, int request_id,
 				 void *data, unsigned int len)
 {
 	struct scsi_cmnd *cmd = tw_dev->srb[request_id];
-	void *buf;
-	unsigned int transfer_len;
-	unsigned long flags = 0;
-	struct scatterlist *sg = scsi_sglist(cmd);
+	unsigned long flags;
 
 	local_irq_save(flags);
-	buf = kmap_atomic(sg_page(sg), KM_IRQ0) + sg->offset;
-	transfer_len = min(sg->length, len);
-
-	memcpy(buf, data, transfer_len);
-
-	kunmap_atomic(buf - sg->offset, KM_IRQ0);
+	scsi_sg_copy_from_buffer(cmd, data, len);
 	local_irq_restore(flags);
 }