dmaengine: pl330: fix issues with big-endian armv7

When running Xilinx Zynq in big-endian mode the pl330 driver
fails to pass the dmatest suite. To fix this, ensure all non
byte values are written in little endian.

As a note, the documentation does not mention if it will do
big-endian descriptor fetches, only that it will swap the
data in flight.

Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
--
Vinod Koul <vinod.koul@intel.com>
Dan Williams <dan.j.williams@intel.com>
DMA List <dmaengine@vger.kernel.org>
Maxime Ripard <maxime.ripard@free-electrons.com>
Jassi Brar <jassisinghbrar@gmail.com>
Liviu Dudau <Liviu.Dudau@arm.com>
Linux ARM Kernel <linux-arm-kernel@lists.infradead.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>