ace: fix DSP panic during startup

pm_device_runtime_get() must be called after pd_intel_adsp_init() is
called for each device, because the latter calls
pm_device_runtime_enable(), which sets the device runtime PM use
count to 0. The current wrong calling order causes a DSP panic
because of an unbalanced pm_device_runtime_put(). Fix this by
delaying pm_device_runtime_get() until the POST_KERNEL initialisation
step.

Fixes commit c3a6274 ("intel_adsp: ace: power: Prevent HST
domain power gating")

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>

soc/xtensa/intel_adsp/ace/multiprocessing.c

@@ -80,14 +80,16 @@ void soc_mp_init(void)
 		IDC[i].agents[0].ipc.ctl = BIT(0); /* IPCTBIE */
 	}
 
-	int ret = pm_device_runtime_get(INTEL_ADSP_HST_DOMAIN_DEV);
-	ARG_UNUSED(ret);
-	__ASSERT(ret == 0, "HST power domain resume operation failed.");
-
 	/* Set the core 0 active */
 	soc_cpus_active[0] = true;
 }
 
+static int host_runtime_get(void)
+{
+	return pm_device_runtime_get(INTEL_ADSP_HST_DOMAIN_DEV);
+}
+SYS_INIT(host_runtime_get, POST_KERNEL, 99);
+
 #ifdef CONFIG_ADSP_IMR_CONTEXT_SAVE
 /*
  * Called after exiting D3 state when context restore is enabled.