SECOND/TKSA compatibility fix

c64/kernal/iec/second.s

@@ -14,13 +14,12 @@ SECOND:
 
 #if CONFIG_IEC
 
-	// Due to OPEN/CLOSE/TKSA/SECOND command encoding (see https://www.pagetable.com/?p=1031),
-	// allowed channels are 0-15; report error if out of range
-	cmp #$10
-	bcc !+ 
-	jmp kernalerror_DEVICE_NOT_FOUND // XXX find a better error message for wrong channel (create new one?)
-!:
-	ora #$60
+	// Due to OPEN/CLOSE/TKSA/SECOND command encoding, allowed channels are 0-15; it is the caller
+	// responsibility, hovewer, to provide value ORed with $60
+	// - https://www.lemon64.com/forum/viewtopic.php?t=57694&sid=531ba3592bcffadef2ac8b9162f2e529
+	// - https://www.pagetable.com/?p=1031 (Kernal API description)
+
+	// XXX consider checking whether value is in range (contrary to original ROM implementation)
 
 	jmp common_open_close_unlsn_second