intel_adsp: cavs25: configure access to ALH

For Intel cavs2.5, access from LPGPDMAC to Audio Link Hub
RX/TX registers needs to be explicitly enabled before use.

The logic follow hardware initialization done in
SOF project sof/src/platform/intel/cavs/platform.c

Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>