ASoC: nau8810: Fix incorrect type in assignment and cast to restricted __be16

This issue is reproduced when W=1 build in compiler gcc-12.
The following are sparse warnings:

sound/soc/codecs/nau8810.c:183:25: sparse: warning: incorrect type in assignment
sound/soc/codecs/nau8810.c:183:25: sparse: expected int
sound/soc/codecs/nau8810.c:183:25: sparse: got restricted __be16
sound/soc/codecs/nau8810.c:219:25: sparse: warning: cast to restricted __be16
sound/soc/codecs/nau8810.c:219:25: sparse: warning: cast to restricted __be16
sound/soc/codecs/nau8810.c:219:25: sparse: warning: cast to restricted __be16
sound/soc/codecs/nau8810.c:219:25: sparse: warning: cast to restricted __be16

This issue is not still actively checked by kernel test robot.
Actually, it is same with nau8822's sparse warnings issue.

Signed-off-by: David Lin <CTLIN0@nuvoton.com>
Link: https://lore.kernel.org/r/20231120084227.1766633-1-CTLIN0@nuvoton.com
Signed-off-by: Mark Brown <broonie@kernel.org>