dmaengine: idxd: Remove unused declarations

dmaengine: idxd: Remove unused declarations

Commit c05257b5600b ("dmanegine: idxd: open code the dsa_drv registration")
removed idxd_{un}register_driver() definitions but not the declarations.
Commit 034b3290ba25 ("dmaengine: idxd: create idxd_device sub-driver")
declared idxd_{un}register_idxd_drv() but never implemented it.
Commit 8f47d1a5e545 ("dmaengine: idxd: connect idxd to dmaengine
subsystem") declared idxd_parse_completion_status() but never implemented
it.

Signed-off-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Link: https://lore.kernel.org/r/20230817114135.50264-1-yuehaibing@huawei.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>