The gpiod_lookup_table.table passed to gpiod_add_lookup_table() must
be terminated with an empty entry, add this.

Note we have likely been getting away with this not being present because
the GPIO lookup code first matches on the dev_id, causing most lookups to
skip checking the table and the lookups which do check the table will
find a matching entry before reaching the end. With that said, terminating
these tables properly still is obviously the correct thing to do.

Fixes: f8eb0235 ("x86: pcengines apuv2 gpio/leds/keys platform driver")
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20210806115515.12184-1-hdegoede@redhat.com