ata: fix sparse warning in sata_promise.c

drivers/ata/sata_promise.c:546:15: warning: symbol 'len' shadows an earlier one
drivers/ata/sata_promise.c:538:6: originally declared here

len is set again immediately after the loop, so this is safe.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/sata_promise.c

@@ -543,7 +543,7 @@ static void pdc_fill_sg(struct ata_queued_cmd *qc)
 	idx = 0;
 	for_each_sg(qc->sg, sg, qc->n_elem, si) {
 		u32 addr, offset;
-		u32 sg_len, len;
+		u32 sg_len;
 
 		/* determine if physical DMA addr spans 64K boundary.
 		 * Note h/w doesn't support 64-bit, so we unconditionally