ioatdma: allow all channels to have irq coalescing support

Looks like only the RAID channels are allowed to have irq coalescing support
in the existing code. Fixing that. The ioat3 cleanup code can handle memcpy
ops anyways

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>