Input: axp20x-pek - enable wakeup for all AXP variants

There are many devices, including several mobile battery-powered
devices, using other AXP variants as their PMIC. Allow them to use
the power key as a wakeup source.

Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20200115051253.32603-3-samuel@sholland.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>