When the kernel is more recent than firmware files, it will always
behave in backwards-compatible ways.

Add optional behavior to check if the kernel is older than the
firmware files, so that the kernel fails early instead of attempting
to use new functionality it does not support.
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>