hwmon: (adt7470) Fix PWM auto temp state array and bounds check

hwmon: (adt7470) Fix PWM auto temp state array and bounds check

In pwm_auto_temp_store(), the parsed user input was missing bounds
checks, allowing values > 0xF to overflow into the adjacent channel's
bits. Furthermore, the value was being incorrectly written to the
pwm_automatic state array instead of pwm_auto_temp.

Fix this by rejecting values > 0xF with -EINVAL, and assigning the
value to the correct array only after a successful I2C write.

Reported-by: sashiko-bot@kernel.org
Closes: https://lore.kernel.org/all/20260727034932.0B7C41F000E9@smtp.kernel.org/#t
Fixes: 6f9703d0be16 ("hwmon: add support for adt7470")
Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Link: https://lore.kernel.org/r/20260727-adt7470_fixes-v2-8-598e38a46ba6@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>