With NCQ, there are multiple sg tables, so pp->cmd_tbl_sg doesn't cut
it.  Directly calculate sg table address from pp->cmd_tbl.
Signed-off-by: Tejun Heo <htejun@gmail.com>
        dma_addr_t              cmd_slot_dma;
        void                    *cmd_tbl;
        dma_addr_t              cmd_tbl_dma;
-       struct ahci_sg          *cmd_tbl_sg;
        void                    *rx_fis;
        dma_addr_t              rx_fis_dma;
 };
        pp->cmd_tbl = mem;
        pp->cmd_tbl_dma = mem_dma;
 
-       pp->cmd_tbl_sg = mem + AHCI_CMD_TBL_HDR_SZ;
-
        ap->private_data = pp;
 
        if (hpriv->cap & HOST_CAP_64)
        /*
         * Next, the S/G list.
         */
-       ahci_sg = pp->cmd_tbl_sg;
+       ahci_sg = pp->cmd_tbl + AHCI_CMD_TBL_HDR_SZ;
        ata_for_each_sg(sg, qc) {
                dma_addr_t addr = sg_dma_address(sg);
                u32 sg_len = sg_dma_len(sg);