platform/x86: thinkpad_acpi: Remove always false 'value < 0' statement

Since 'value' is declared as unsigned long, the following statement is
always false.
	value < 0

So let's remove it.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>