dmaengine: idxd: export hw version through sysfs

Some user apps would like to know the hardware version in order to
determine the variation of the hardware. Export the hardware version number
to userspace via sysfs.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/158696714008.39484.13401950732606906479.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: Vinod Koul <vkoul@kernel.org>