ioatdma: Add 64bit chansts register read for ioat v3.3.

The channel status register for v3.3 is now 64bit. Use readq if available
on v3.3 platforms.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Dan Williams <djbw@fb.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>