dmaengine: idxd: Add idxd_device_config_save() and idxd_device_config_restore() helpers

Add the helpers to save and restore IDXD device configurations.

These helpers will be called during Function Level Reset (FLR) processing.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20241122233028.2762809-4-fenghua.yu@intel.com


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