platform/x86: compal-laptop: Initialize "value" in ec_read_u8()

In function ec_read_u8(), variable "value" could be uninitialized
if ec_read() fails. However, "value" is returned directly and used
in its callers. This is potentially unsafe.

Signed-off-by: Yizhuo <yzhai003@ucr.edu>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>