ASoC: wm_adsp: Use __leXX for little endian data

Using uXX for little endian data, was triggering some warnings through
sparse:

sound/soc/codecs/wm_adsp.c:716:26: sparse: cast to restricted __le16
sound/soc/codecs/wm_adsp.c:736:23: sparse: cast to restricted __le16
sound/soc/codecs/wm_adsp.c:739:23: sparse: cast to restricted __le32

Correct this by changing the casts to use __leXX instead of uXX.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>