ASoC: SOF: loader: snd_sof_fw_parse_ext_data log warning on unknown header

Added warning log when found some unknown FW boot ext header,
to improve debuggability.

Signed-off-by: Karol Trzcinski <karolx.trzcinski@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20191210004854.16845-3-pierre-louis.bossart@linux.intel.com


Signed-off-by: Mark Brown <broonie@kernel.org>