clearfog: document a gpio-hog bug

Change-Id: I830f4ca4f0df22fdb3803b4cc4f780c0cc00575a
diff --git a/board/czechlight/clearfog/sdn-roadm-clearfog.dtsi b/board/czechlight/clearfog/sdn-roadm-clearfog.dtsi
index 5342091..dfaa15c 100644
--- a/board/czechlight/clearfog/sdn-roadm-clearfog.dtsi
+++ b/board/czechlight/clearfog/sdn-roadm-clearfog.dtsi
@@ -182,6 +182,7 @@
 				"EDFA2_PUMP_TEMP_A";
 		};
 
+		// FIXME: this hogs both .1 and .2 chips' #6 pin...
 		i2c_xor_ready {
 			gpio-hog;
 			gpios = <6 GPIO_ACTIVE_HIGH>;