hwmon: (lm90) Use generic i2c reads during detection

As indirectly reported by Olof Johansson, the lm90 driver uses a
custom i2c read function even during detection, at which point we
don't know yet what device we're talking with. It would make more
sense to only use the generic i2c read function at this point, so
that we don't log irrelevant errors on misdetection.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>