hwmon: (g762) Fix overflows and crash seen when writing limit attributes

hwmon: (g762) Fix overflows and crash seen when writing limit attributes

commit 4fccd4a1e8944033bcd7693ea4e8fb478cd2059a upstream.

Fix overflows seen when writing into fan speed limit attributes.
Also fix crash due to division by zero, seen when certain very
large values (such as 2147483648, or 0x80000000) are written
into fan speed limit attributes.

Fixes: 594fbe713bf60 ("Add support for GMT G762/G763 PWM fan controllers")
Cc: Arnaud Ebalard <arno@natisbad.org>
Reviewed-by: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>