sb/intel/common: Implement acpi_is_wakeup_s3()

acpi_is_wakeup_s3() requires acpi_get_sleep_type().

Change-Id: Ibe01863e685bcbc9652a72be0632cfbd83e18380
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52929
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>

src/southbridge/intel/common/pmbase.c

@@ -75,6 +75,11 @@ u8 read_pmbase8(const u8 addr)
 	return inb(lpc_get_pmbase() + addr);
 }
 
+int acpi_get_sleep_type(void)
+{
+	return acpi_sleep_from_pm1(read_pmbase32(PM1_CNT));
+}
+
 int platform_is_resuming(void)
 {
 	u16 reg16 = read_pmbase16(PM1_STS);