ASoC: Intel: Store the entry_point read from FW file

To enable some modules from other than base FW, according
to FW interface spec, we need pass the correct entry point
param to FW, so here store the entry_point read from FW
file for later usage.

Signed-off-by: Jie Yang <yang.jie@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>