dmaengine: idxd: fix bus_probe() and bus_remove() for dsa_bus

dmaengine: idxd: fix bus_probe() and bus_remove() for dsa_bus

Current implementation have put all the code that should be in a driver
probe/remove in the bus probe/remove function. Add ->probe() and ->remove()
support for the dsa_drv and move all those code out of bus probe/remove.
The change does not split out the distinction between device sub-driver and
wq sub-driver. It only cleans up the bus calls. The split out will be
addressed in follow on patches.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/162637463586.744545.5806250155539938643.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>