ASoC: cs35l35: Correctly handle 0 for bst_ipk

Zero is a totally valid value to specify for the bst_ipk, as such we
should append CS35L35_VALID_PDATA to ensure that it actually makes it
into the register value.
Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/cs35l35.c

@@ -1269,7 +1269,7 @@ static int cs35l35_handle_of_data(struct i2c_client *i2c_client,
 			return -EINVAL;
 		}
 
-		pdata->bst_ipk = (val32 - 1680) / 110;
+		pdata->bst_ipk = ((val32 - 1680) / 110) | CS35L35_VALID_PDATA;
 	}
 
 	ret = of_property_read_u32(np, "cirrus,boost-ind-nanohenry", &val32);