In z_phys_unmap(), the call to virt_region_free() is not using
aligned virtual address and space. This can result in freeing
smaller region that allocated given that inputs to z_phys_unmap()
may not be aligned. So use the already calculated aligned
virtual address and size as input to virt_region_free().
Note that the assertion and if-block in virt_region_free() to
check whether the to-be-unmapped region is within the virtual
memory region needs to be trimmed by one byte at the end.
The assertion and if-block are checking against the region
end address but (start + size) is just one byte over the end.
So subtract one.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>