dmaengine: ioatdma: support latency tolerance report (LTR) for v3.4

IOATDMA 3.4 supports PCIe LTR mechanism. The registers are non-standard
PCIe LTR support. This needs to be setup in order to not suffer performance
impact and provide proper power management. The channel is set to active
when it is allocated, and to passive when it's freed.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>