ASoC: rt5651: Variable "ret" in function rt5651_i2c_probe() could be uninitialized

In function rt5651_i2c_probe(), local variable "ret" could
be uninitialized if function regmap_read() returns -EINVAL.
However, this value is used in if statement. This is
potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@ucr.edu>
Signed-off-by: Mark Brown <broonie@kernel.org>