QmlDesigner: Do not use deprecated functionality.

toAscii -> toLatin1

Change-Id: Ib709f046fac965af6ee82c1432588e6467cd711b
Reviewed-by: Marco Bubke <marco.bubke@digia.com>

src/plugins/qmldesigner/designercore/model/propertyparser.cpp

@@ -60,8 +60,8 @@ static uchar fromHex(const uchar c, const uchar c2)
 
 static uchar fromHex(const QString &s, int idx)
 {
-    uchar c = s.at(idx).toAscii();
-    uchar c2 = s.at(idx + 1).toAscii();
+    uchar c = s.at(idx).toLatin1();
+    uchar c2 = s.at(idx + 1).toLatin1();
     return fromHex(c, c2);
 }