dmaengine: idxd: check device state before issue command

Add device state check before executing command. Without the check the
command can be issued while device is in halt state and causes the driver to
block while waiting for the completion of the command.

Reported-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Sanjay Kumar <sanjay.k.kumar@intel.com>
Fixes: 0d5c10b4

 ("dmaengine: idxd: add work queue drain support")
Link: https://lore.kernel.org/r/161219313921.2976211.12222625226450097465.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>