intel_adsp/ace: power: pad the hpsram_mask passed to power_down

The power_down() function will lock dcache for the hpsram_mask
array. On some platforms, the dcache lock will fail if the array
is on cache line that can be used for window register context
saves.

Work around this by aligning and padding the hpsram_mask to cacheline
size.

Link: https://github.com/thesofproject/sof/issues/9268


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