media: dvb: Fix error handling of SDMX API failures

When setting of key-ladder index fails, there's no need
to fail starting of the filter since it could only mean
that decryption might fail if encrypted packets are encountered.

In addition, if closing SDMX session fails, SDMX TZ application
might be removed anyhow, therefore we should clear reference
counting of SDMX session so that it is re-opened if requested
in the future.

Change-Id: I17e1ce62b72910e2086d948807af969725c6f18b
Signed-off-by: Hamad Kadmany <hkadmany@codeaurora.org>