soc: imx: gpcv2: support system suspend/resume

Our usage of runtime PM to control the hierarchy of power domains is
slightly unusual and means that powering up a domain may fail in early
system resume, as runtime PM is still disallowed at this stage.

However the system suspend/resume path takes care of powering down/up
the power domains in the order defined by the device parent/child and
power-domain provider/consumer hierarachy. So we can just runtime
resume all our power-domain devices to allow the power-up to work
properly in the resume path. System suspend will still disable all
domains as intended.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>