ACPI S3: Replace acpi_is_wakeup()

It was supposed to return true for both S2 and S3, but
level S2 was never stored in acpi_slp_type or otherwise
implemented.

Change-Id: Ida0165e647545069c0d42d38b9f45a95e78dacbe
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/47693
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/acpi/acpi.h

@@ -1070,12 +1070,10 @@ static inline int acpi_is_wakeup_s3(void)
 	return (acpi_get_sleep_type() == ACPI_S3);
 }
 #else
-int acpi_is_wakeup(void);
 int acpi_is_wakeup_s3(void);
 #endif
 
 #else
-static inline int acpi_is_wakeup(void) { return 0; }
 static inline int acpi_is_wakeup_s3(void) { return 0; }
 #endif