ASoC: max9867: make array ni_div static const

The array ni_div does not need to be in global scope and is not
modified, so make it static const.

Cleans up sparse warning:
"symbol 'ni_div' was not declared. Should it be static?"
Signed-off-by: NColin Ian King <colin.king@canonical.com>
Acked-By: NVinod Koul <vinod.koul@intel.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/max9867.c

@@ -132,7 +132,7 @@ enum rates {
 	pcm_rate_48, max_pcm_rate,
 };
 
-struct ni_div_rates {
+static const struct ni_div_rates {
 	u32 mclk;
 	u16 ni[max_pcm_rate];
 } ni_div[] = {