firmware: arm_scmi: power_control: Ensure SCMI_SYSPOWER_IDLE is set early during resume

[ Upstream commit 9a0658d3 ]

Fix a race condition where a second suspend notification from another
SCMI agent wakes the system before SCMI_SYSPOWER_IDLE is set, leading
to ignored suspend requests. This is due to interrupts triggering early
execution of `scmi_userspace_notifier()` before the SCMI state is updated.

To resolve this, set SCMI_SYSPOWER_IDLE earlier in the device resume
path, prior to `thaw_processes()`. This ensures the SCMI state is
correct when the notifier runs, allowing the system to suspend again
as expected.

On some platforms using SCMI, SCP cannot distinguish between CPU idle
and suspend since both result in cluster power-off. By explicitly setting
the idle state early, the Linux SCMI agent can correctly re-suspend in
response to external notifications.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Message-Id: <20250704-scmi-pm-v2-2-9316cec2f9cc@nxp.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>