ASoC: rt1015: check the return value of regmap_read during i2c probe

In some projects, the device ID register is not read correctly.
This patch helps to verify the issue is caused from i2c host or client.

Signed-off-by: Derek Fang <derek.fang@realtek.com>
Link: https://lore.kernel.org/r/20201209091308.2823-1-derek.fang@realtek.com
Signed-off-by: Mark Brown <broonie@kernel.org>