[media] solo6x10: The size of the thresholds ioctls was too large

On powerpc the maximum size for the ioctl argument is 8191, and it was
8192. However, the 64x64 array of threshold values is more than is actually
needed in practice for PAL and NTSC formats. A 45x45 array will do just fine.
So change the size accordingly to fix this problem.

Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>