cpuidle: riscv-sbi: Opt-out from genpd's common ->sync_state() support

The riscv-sbi-domain implements its own specific ->sync_state() callback.
Let's set the GENPD_FLAG_NO_SYNC_STATE to inform genpd about it.

Moreover, let's call of_genpd_sync_state() to make sure genpd tries to
power off unused PM domains.

Cc: Anup Patel <anup@brainfault.org>
Cc: linux-riscv@lists.infradead.org
Tested-by: Hiago De Franco <hiago.franco@toradex.com> # Colibri iMX8X
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> # TI AM62A,Xilinx ZynqMP ZCU106
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Rahul Pathak <rpathak@ventanamicro.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Link: https://lore.kernel.org/r/20250701114733.636510-12-ulf.hansson@linaro.org

drivers/cpuidle/cpuidle-riscv-sbi.c

@@ -347,11 +347,16 @@ deinit:
 
 static void sbi_cpuidle_domain_sync_state(struct device *dev)
 {
+	struct sbi_pd_provider *pd_provider;
+
 	/*
 	 * All devices have now been attached/probed to the PM domain
 	 * topology, hence it's fine to allow domain states to be picked.
 	 */
 	sbi_cpuidle_pd_allow_domain_state = true;
+
+	list_for_each_entry(pd_provider, &sbi_pd_providers, link)
+		of_genpd_sync_state(pd_provider->node);
 }
 
 #ifdef CONFIG_DT_IDLE_GENPD
@@ -396,7 +401,8 @@ static int sbi_pd_init(struct device_node *np)
 	if (!pd_provider)
 		goto free_pd;
 
-	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN;
+	pd->flags |= GENPD_FLAG_IRQ_SAFE | GENPD_FLAG_CPU_DOMAIN |
+		     GENPD_FLAG_NO_SYNC_STATE;
 
 	/* Allow power off when OSI is available. */
 	if (sbi_cpuidle_use_osi)