[media] dib8000: improve block statistics

PER/UCB statistics are collected once on each 1 second.
However, it doesn't provide the total number of packets
needed to calculate PER.

Yet, as we know the bit rate, it is possible to estimate
such number. So, do it.

Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>
Acked-by: Patrick Boettcher <pboettcher@kernellabs.com>