dmaengine: idxd: fix misc interrupt handler thread unmasking

Fix unmasking of misc interrupt handler when completing normal. It exits
early and skips the unmasking with the current implementation. Fix to
unmask interrupt when exiting normally.

Fixes: bfe1d560

 ("dmaengine: idxd: Init and probe for Intel data accelerators")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/159311256528.855.11527922406329728512.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>