ioat2,3: put channel hardware in known state at init

Put the ioat2 and ioat3 state machines in the halted state with all
errors cleared.

The ioat1 init path is not disturbed for stability, there are no
reported ioat1 initiaization issues.

Cc: <stable@kernel.org>
Reported-by: Roland Dreier <rdreier@cisco.com>
Tested-by: Roland Dreier <rdreier@cisco.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
diff --git a/drivers/dma/ioat/registers.h b/drivers/dma/ioat/registers.h
index f015ec1..e8ae63b 100644
--- a/drivers/dma/ioat/registers.h
+++ b/drivers/dma/ioat/registers.h
@@ -27,6 +27,7 @@
 
 #define IOAT_PCI_DEVICE_ID_OFFSET		0x02
 #define IOAT_PCI_DMAUNCERRSTS_OFFSET		0x148
+#define IOAT_PCI_CHANERR_INT_OFFSET		0x180
 #define IOAT_PCI_CHANERRMASK_INT_OFFSET		0x184
 
 /* MMIO Device Registers */