cards: remove "auto_once" from possible ctype options

The card_detect function in cards.py allows to specify the card type or
use the hints "auto" and "auto_once" to trigger autodetection of the
card. However, "auto_once" has no effect and is not used by any caller,
so lets remove it.

Change-Id: Iea726f51e5ddb43d8a4da2672552fff38e29b006
diff --git a/pySim/cards.py b/pySim/cards.py
index 2f96ee1..95352ff 100644
--- a/pySim/cards.py
+++ b/pySim/cards.py
@@ -1564,7 +1564,7 @@
 	card = None
 	ctypes = dict([(kls.name, kls) for kls in _cards_classes])
 
-	if ctype in ("auto", "auto_once"):
+	if ctype == "auto":
 		for kls in _cards_classes:
 			card = kls.autodetect(scc)
 			if card:
@@ -1576,9 +1576,6 @@
 			print("Autodetection failed")
 			return None
 
-		if ctype == "auto_once":
-			ctype = card.name
-
 	elif ctype in ctypes:
 		card = ctypes[ctype](scc)