[SG] Update drivers to use sg helpers

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/scsi/fdomain.c b/drivers/scsi/fdomain.c
index 5d282e6..2cd6b49 100644
--- a/drivers/scsi/fdomain.c
+++ b/drivers/scsi/fdomain.c
@@ -1321,7 +1321,7 @@
 	    if (current_SC->SCp.buffers_residual) {
 	       --current_SC->SCp.buffers_residual;
 	       ++current_SC->SCp.buffer;
-	       current_SC->SCp.ptr = page_address(current_SC->SCp.buffer->page) + current_SC->SCp.buffer->offset;
+	       current_SC->SCp.ptr = sg_virt(current_SC->SCp.buffer);
 	       current_SC->SCp.this_residual = current_SC->SCp.buffer->length;
 	    } else
 		  break;
@@ -1354,7 +1354,7 @@
 	     && current_SC->SCp.buffers_residual) {
 	    --current_SC->SCp.buffers_residual;
 	    ++current_SC->SCp.buffer;
-	    current_SC->SCp.ptr = page_address(current_SC->SCp.buffer->page) + current_SC->SCp.buffer->offset;
+	    current_SC->SCp.ptr = sg_virt(current_SC->SCp.buffer);
 	    current_SC->SCp.this_residual = current_SC->SCp.buffer->length;
 	 }
       }
@@ -1439,8 +1439,7 @@
 
    if (scsi_sg_count(current_SC)) {
 	   current_SC->SCp.buffer = scsi_sglist(current_SC);
-	   current_SC->SCp.ptr = page_address(current_SC->SCp.buffer->page)
-		   + current_SC->SCp.buffer->offset;
+	   current_SC->SCp.ptr = sg_virt(current_SC->SCp.buffer);
 	   current_SC->SCp.this_residual    = current_SC->SCp.buffer->length;
 	   current_SC->SCp.buffers_residual = scsi_sg_count(current_SC) - 1;
    } else {