platform/x86: intel-vbtn: Reset wakeup capable flag on removal
The intel-vbtn device will not be able to wake up the system any more
after removing the notify handler provided by its driver, so make
its sysfs attributes reflect that.
Fixes: d793746b4f68 (platform: x86: intel-vbtn: Wake up the system from suspend-to-idle) Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>