dmaengine: idxd: Remove unused idxd_(un)register_bus_type

idxd_register_bus_type() and idxd_unregister_bus_type() have been unused
since 2021's
commit d9e5481f ("dmaengine: dsa: move dsa_bus_type out of idxd driver
to standalone")

Remove them.

Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20241221141635.69412-1-linux@treblig.org


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