mm: intel: adsp: simplify code in mm_drv_intel_adsp_regions.c

temporary_table is a trivial copy of virtual_memory_regions, it isn't
clear why it's needed. All the more that it's freely mixed with
virtual_memory_regions itself. Also change a variable name to avoid
confusion and improve indentation.

Signed-off-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>