platform/x86: huawei-wmi: huawei_wmi can be static

Fixes: 7532afb35012 ("platform/x86: huawei-wmi: Move to platform driver")
Signed-off-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>