soc: intel_adsp: use Z_KERNEL_STACK_BUFFER instead of...
soc: intel_adsp: use Z_KERNEL_STACK_BUFFER instead of...

...Z_THREAD_STACK_BUFFER.

This is currently a symbolic change as Z_THREAD_STACK_BUFFER
is simply an alias to Z_KERNEL_STACK_BUFFER without userspace,
and Xtensa does not support userspace at the moment.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr