[media] cx88: notch filter control fixes

This patch reduces the number of available choices for the notch filter type control
so that the standard-specific filter types cannot be selected. It is now limited to
being either 0 (4xFsc, the default) or 1 (square pixel optimized).
The patch also removes the initialization of this control from cx88_reset(), since
that is already done by init_controls(), which is called by cx8800_initdev().

Signed-off-by: Istvan Varga <istvan_v@mailbox.hu>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>