soc/amd/common/pm/pmlib: use PM register mapping in ACPIMMIO region

In all SoC pm_set_power_failure_state gets called either after a call to
enable_acpimmio_decode_pm04() or the ACPIMMIO mapping is already enabled
after reset on the SoC. This allows to use pm_read8 and pm_write8 that
use the ACPIMMIO mapping of the PM registers instead of pm_io_read8 and
pm_io_write8 which won't work on Phoenix and Glinda due to the IO ports
used on older generations to access to the PM registers not being
implemented any more.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: Id0d0523d2c4920da41b3fb73cf62f22a60f1643a
Reviewed-on: https://review.coreboot.org/c/coreboot/+/76463
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin L Roth <gaumless@gmail.com>

src/soc/amd/common/block/pm/pmlib.c

@@ -37,5 +37,5 @@ void pm_set_power_failure_state(void)
 		break;
 	}
 
-	pm_io_write8(PM_RTC_SHADOW_REG, pwr_fail);
+	pm_write8(PM_RTC_SHADOW_REG, pwr_fail);
 }