firmware: dcdbas: Add support for WSMT ACPI table

If the WSMT ACPI table is present and indicates that a fixed communication
buffer should be used, use the firmware-specified buffer instead of
allocating a buffer in memory for communications between the dcdbas driver
and firmare.

Signed-off-by: Stuart Hayes <stuart.w.hayes@gmail.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>