The Kconfig option belongs closer to the corresponding implementation,
hence let's move it from the soc subsystem to the pmdomain subsystem.

Cc: Hector Martin <marcan@marcan.st>
Cc: Sven Peter <sven@svenpeter.dev>
Cc: Alyssa Rosenzweig <alyssa@rosenzweig.io>
Cc: <asahi@lists.linux.dev>
Reviewed-by: Eric Curtin <ecurtin@redhat.com>
Reviewed-by: Neal Gompa <neal@gompa.dev>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>