fsl_dma: fix support for 83xx DMA engine

Commit 359ec493

 broke support for the
Freescale DMA engine on the 83xx parts. This is due to using registers
which do not exist on 83xx. Remove the attribute register accesses from
the 83xx build.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Cc: York Sun <yorksun@freescale.com>
Cc: Peter Tyser <ptyser@xes-inc.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Kim Phillips <kim.phillips@freescale.com>