intel_scu_ipc: return -EIO for error condition in busy_loop

Signed-off-by: NHong Liu <hong.liu@intel.com>
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NMatthew Garrett <mjg@redhat.com>

drivers/platform/x86/intel_scu_ipc.c

@@ -148,7 +148,10 @@ static inline int busy_loop(void) /* Wait till scu status is busy */
 			return -ETIMEDOUT;
 		}
 	}
-	return (status >> 1) & 1;
+	if ((status >> 1) & 1)
+		return -EIO;
+
+	return 0;
 }
 
 /* Read/Write power control(PMIC in Langwell, MSIC in PenWell) registers */