ASoC: SOF: topology: Prevent NULL pointer dereference with no TLV

ASoC: SOF: topology: Prevent NULL pointer dereference with no TLV

When there is no TLV data in topology, extracting the TLV data
could result in a NULL pointer exception. Prevent this by making
sure that the TLV data exists before extracting it.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Paul Olaru <paul.olaru@oss.nxp.com>
Reviewed-by: Bard Liao <bard.liao@intel.com>
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Link: https://lore.kernel.org/r/20210201093128.1226603-1-kai.vehmanen@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>