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