cryptoworks/viaccess: Run EMM reassembly before writing EMM in the card.

Before this patch EMM reasembly was only run by dvbapi client.

This means that any other client (via netcamd, cs378x, cccam) was
expected to perform its own EMM reassembly otherwise the card
was unable to write some EMMs which needed preprocessing (reassemblation).

This commit moves EMM reassembly where it belongs - just before the
EMM is written in the card. That simplifies client logic (no more
knowledge of CW and VIA EMMs) and allows cards to be updated via
any network protocol.

The changes were tested with Swiss Viacess card and Digiturk Cryptoworks
card. Both cards received EMMs and were updated via cs378x protocol
using tsdecrypt as client.