ASoC: cs42xx8: Check return value of regmap_read and report correct chipid value

Fix checking return value of regmap_read().
Also fix reporting the chip_id value. CS42XX8_CHIPID_CHIP_ID_MASK is 0xF0,
so the chip_id value is (val & CS42XX8_CHIPID_CHIP_ID_MASK) >> 4).

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Acked-by: Paul Handrigan <paul.handrigan@cirrus.com>
Acked-by: Brian Austin <brian.austin@cirrus.com>
Acked-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>