Unlike keys where userspace only reacts to keypresses, userspace may act
on switches in both (0 and 1) of their positions.

For example if a SW_TABLET_MODE switch is registered then GNOME will not
automatically show the onscreen keyboard when a text field gets focus on
touchscreen devices when SW_TABLET_MODE reports 0 and when SW_TABLET_MODE
reports 1 libinput will block (filter out) builtin keyboard and touchpad
events.

So to avoid unwanted side-effects EV_SW type inputs should only be
registered if they are actually present, only register SW_CAMERA_LENS_COVER
if it is actually there.

Fixes: 8af9fa37 ("platform/x86: dell-privacy: Add support for Dell hardware privacy")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20221221220724.119594-2-hdegoede@redhat.com