fsldma: use a valid 'device' for dma_pool_create

The dmaengine sysfs implementation was fixed to support proper
lifetime rules which means that the current:

new_fsl_chan->dev = &new_fsl_chan->common.dev->device;

...retrieves a NULL pointer because new_fsl_chan->common.dev has not
been allocated at this point.  So, set new_fsl_chan->dev to a valid
device.

Cc: Li Yang <leoli@freescale.com>
Cc: Zhang Wei <zw@zh-kernel.org>
Reported-by: Ira Snyder <iws@ovro.caltech.edu>
Tested-by: Ira Snyder <iws@ovro.caltech.edu>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>