sample: syst: Add intel_adsp_cavs support

Adding configurations for enabling this sample project on cavs
platforms. This patch also contains a fix to mipi_syst library
which resolves the memory alignment issue across different
architectures.

Fixes #43344

Signed-off-by: Aastha Grover <aastha.grover@intel.com>
Signed-off-by: Peter Mitsis <peter.mitsis@intel.com>