Use a mmap_region_t as parameter instead of getting a parameter for each
structure member. This reduces the scope of changes when adding members
to mmap_region_t.

Also align on the convention of using mm_cursor as a variable name for
the currently inspected region when iterating on the region array.

Change-Id: If40bc4351b56c64b214e60dda27276d11ce9dbb3
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>