xtensa: intel_adsp: make common rimage_modules.c cavs-specific

Make xtensa/intel_adsp/common/rimage_modules.c CAVS-specific by adding a
guard.

Signed-off-by: Konrad Leszczynski <konrad.leszczynski@intel.com>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>