ACPI: Add helpers for CBMEM_ID_POWER_STATE

Create uniform logging for the (unlikely) case of a CBMEM
entry disappearing.

Change-Id: I7c5414a03d869423c8ae5192a990fde5f9582f2d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49817
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/intel/broadwell/pch/elog.c

@@ -1,7 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 
+#include <acpi/acpi_pm.h>
 #include <bootstate.h>
-#include <cbmem.h>
 #include <console/console.h>
 #include <stdint.h>
 #include <elog.h>
@@ -106,13 +106,10 @@ static void pch_log_power_and_resets(const struct chipset_power_state *ps)
 
 static void pch_log_state(void *unused)
 {
-	struct chipset_power_state *ps = cbmem_find(CBMEM_ID_POWER_STATE);
+	const struct chipset_power_state *ps;
 
-	if (ps == NULL) {
-		printk(BIOS_ERR, "Not logging power state information. "
-		       "Power state not found in cbmem.\n");
+	if (acpi_pm_state_for_elog(&ps) < 0)
 		return;
-	}
 
 	/* Power and Reset */
 	pch_log_power_and_resets(ps);