[media] solo6x10: Approximate frame intervals with non-standard denominator

Instead of falling back to 1/25 (PAL) or 1/30 (NTSC).

Signed-off-by: Ismael Luceno <ismael.luceno@corp.bluecherry.net>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>