[media] it913x: endpoint size changes

Previously endpoint had been aligned to packet size (128)

Some early it9135 devices appear to have problems with this.

This patch now aligns with mpeg TS size (188)

With the pid filter off max size is increased to the maxmium
size (348 * 188)

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>