dmaengine: idxd: fix wq size store permission state

WQ size can only be changed when the device is disabled. Current code
allows change when device is enabled but wq is disabled. Change the check
to detect device state.

Fixes: c52ca478

 ("dmaengine: idxd: add configuration component of driver")
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/161782558755.107710.18138252584838406025.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>