dmaengine: idxd: Refactor halt handler

Define a halt handling helper idxd_halt(). Refactor the halt interrupt
handler to call the helper. This will simplify the Function Level
Reset (FLR) code.

No functional change.

Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/20241122233028.2762809-5-fenghua.yu@intel.com


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