ASoC: Intel: Move extended fw base and size fields in struct sst_pdata

Move fw_base and fw_size fields in struct sst_pdata under ACPI data for
clarifying that these are not related to firmware file but for platform
specific extended firmware area reserved by the BIOS.

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Mark Brown <broonie@linaro.org>