V4L/DVB: saa5246a/saa5249: Remove obsolete teletext drivers

These old i2c teletext drivers are not supported by any hardware and cannot be
tested anymore.

Note that while the mxb board seemingly used the saa5246a driver, in reality
this teletext driver never worked.

These drivers are removed as part of the vtx feature removal, originally
scheduled for 2.6.35.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>