[SG] Update drivers to use sg helpers

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/drivers/scsi/wd33c93.c b/drivers/scsi/wd33c93.c
index 0e8e642..fdbb92d 100644
--- a/drivers/scsi/wd33c93.c
+++ b/drivers/scsi/wd33c93.c
@@ -410,8 +410,7 @@
 	if (cmd->use_sg) {
 		cmd->SCp.buffer = (struct scatterlist *) cmd->request_buffer;
 		cmd->SCp.buffers_residual = cmd->use_sg - 1;
-		cmd->SCp.ptr = page_address(cmd->SCp.buffer->page) +
-		    cmd->SCp.buffer->offset;
+		cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
 		cmd->SCp.this_residual = cmd->SCp.buffer->length;
 	} else {
 		cmd->SCp.buffer = NULL;
@@ -745,8 +744,7 @@
 		++cmd->SCp.buffer;
 		--cmd->SCp.buffers_residual;
 		cmd->SCp.this_residual = cmd->SCp.buffer->length;
-		cmd->SCp.ptr = page_address(cmd->SCp.buffer->page) +
-		    cmd->SCp.buffer->offset;
+		cmd->SCp.ptr = sg_virt(cmd->SCp.buffer);
 	}
 	if (!cmd->SCp.this_residual) /* avoid bogus setups */
 		return;