iop-adma: Corrected array overflow in RAID6 Xscale(R) test.

Bug: cppcheck reported overflow in array assignment (for loop walks
0 to IOP_ADMA_NUM_SRC_TEST+2, array size is IOP_ADMA_NUM_SRC_TEST).

Reported as: https://bugzilla.kernel.org/show_bug.cgi?id=42677

Test code pq_src array was grown by two elements to correspond with actual
usage (IOP_ADMA_NUM_SRC_TEST+2), stack consumption was kept constant by
modifying the pq_dest two element array which is only used when pq_src
is referenced up to IOP_ADMA_NUM_SRC_TEST elements into the address
of the new last two elements of the pq_src array. This is presumed to
be the original intent but would be reliant on compilers always having
pq_dest contiguous with the final element of pq_src.

Note: This is a re-send of a request for review from two weeks ago.
Looking for review (or shootdown), adding LKML to list for a wider
audience. Thanks.

Updated per review comments of Sergei Shtylyov <sshtylyov@mvista.com>
Signed-off-by: Don Morris <don.morris@hp.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/dma/iop-adma.c

@@ -1271,8 +1271,8 @@ iop_adma_pq_zero_sum_self_test(struct iop_adma_device *device)
 	struct page **pq_hw = &pq[IOP_ADMA_NUM_SRC_TEST+2];
 	/* address conversion buffers (dma_map / page_address) */
 	void *pq_sw[IOP_ADMA_NUM_SRC_TEST+2];
-	dma_addr_t pq_src[IOP_ADMA_NUM_SRC_TEST];
-	dma_addr_t pq_dest[2];
+	dma_addr_t pq_src[IOP_ADMA_NUM_SRC_TEST+2];
+	dma_addr_t *pq_dest = &pq_src[IOP_ADMA_NUM_SRC_TEST];
 
 	int i;
 	struct dma_async_tx_descriptor *tx;