platform/x86: (eeepc-laptop) Replace SENSORS_LIMIT with clamp_val

SENSORS_LIMIT and clamp_val have the same functionality, so retire SENSORS_LIMIT
as it is no longer needed.

The change reduces text size by 26 bytes and bss size by 16 bytes on x86_86
builds.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>