dmaengine: dw_dma: fix endianess for DT xlate function

As reported by Wu Fengguang's build robot tracking sparse warnings, the
dma_spec arguments in the dw_dma_xlate are already byte swapped on
little-endian platforms and must not get swapped again. This code is
currently not used anywhere, but will be used in Linux 3.10 when the
ARM SPEAr platform starts using the generic DMA DT binding.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>