Change remaining uses of {to,from}Ascii to {to,from}Latin1 [QtNetwork]

Change remaining uses of {to,from}Ascii to {to,from}Latin1 [QtNetwork]

This operation should be a no-op anyway, since at this point in time,
the fromAscii and toAscii functions simply call their fromLatin1 and
toLatin1 counterparts.

Task-number: QTBUG-21872
Change-Id: I94cc301ea75cc689bcb6e2d417120cf14e36808d
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
Reviewed-by: Shane Kearns <shane.kearns@accenture.com>
Reviewed-by: Richard J. Moore <rich@kde.org>