ASoC: adau1977: Fix truncation warning on 64 bit architectures

Negating ADAU1977_BLOCK_POWER_SAI_LDO_EN creates an unsigned long constant
with all bits set which on 64 bit architectures needs to be truncated to
an unsigned int, generating a warning. Add an explicit cast since we know
this is OK.
Signed-off-by: NMark Brown <broonie@linaro.org>
Acked-by: NLars-Peter Clausen <lars@metafoo.de>

sound/soc/codecs/adau1977.c

@@ -968,7 +968,7 @@ int adau1977_probe(struct device *dev, struct regmap *regmap,
 	if (adau1977->dvdd_reg)
 		power_off_mask = ~0;
 	else
-		power_off_mask = ~ADAU1977_BLOCK_POWER_SAI_LDO_EN;
+		power_off_mask = (unsigned int)~ADAU1977_BLOCK_POWER_SAI_LDO_EN;
 
 	ret = regmap_update_bits(adau1977->regmap, ADAU1977_REG_BLOCK_POWER_SAI,
 				power_off_mask, 0x00);