Previously the *_phys fields were of type ipack_addr_space, which use
void pointers to refer to memory addresses. Since the *_phys fields
refer to unmapped memory, this is not correct. Introduce a new struct
ipack_region (which uses phys_addr_t to refer to the start of a region)
and use that as a replacement for struct ipack_addr_space.
struct ipack_region is defined in ipack.h because it is planned to later
expose the physical addressed to the IPack Module drivers.