dmaengine: idxd: remove interrupt disable for cmd_lock

The cmd_lock spinlock is not being used in hard interrupt context. There is
no need to disable irq when acquiring the lock. Convert all cmd_lock
acquisition to plain spin_lock() calls.

Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/162984027930.1939209.15758413737332339204.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>