gpiolib: acpi: Add missing __init(const) markers to initcall-s

The gpiolib ACPI code uses 2 initcall-s and the called function
(and used DMI table) is missing __init(const) markers.

This commit fixes this freeing up some extra memory once the kernel
has completed booting.

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20200325103956.109284-2-hdegoede@redhat.com


Signed-off-by: Linus Walleij <linus.walleij@linaro.org>