pmdomain: Prepare to move Kconfig files into the pmdomain subsystem

Rather than having the various Kconfig files for the genpd providers
sprinkled across subsystems, let's prepare to move them into the pmdomain
subsystem along with the implementations.
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/Kconfig

@@ -175,6 +175,8 @@ source "drivers/soundwire/Kconfig"
 
 source "drivers/soc/Kconfig"
 
+source "drivers/pmdomain/Kconfig"
+
 source "drivers/devfreq/Kconfig"
 
 source "drivers/extcon/Kconfig"

drivers/pmdomain/Kconfig

+# SPDX-License-Identifier: GPL-2.0-only
+menu "PM Domains"
+
+endmenu