We should only add section attribute to the list of section attributes
if we successfully created corresponding sysfs attribute.

Fixes: 049a59db ("firmware: Google VPD sysfs driver")
Signed-off-by: NDmitry Torokhov <dmitry.torokhov@gmail.com>
Reviewed-by: NGuenter Roeck <groeck@chromium.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>