Fixes build error:
map/vm_region.c: In function 'vm_map_region':
map/vm_region.c:128:16: error: pointer of type 'void *' used in arithmetic [-Werror=pointer-arith]
128 | return vaddr + (MM_PGMASK & paddr);
| ^
cc1: all warnings being treated as errors
This revises vm_map_region() by accepting unaligned paddr, which is
aligned-down before mapping and in-page offset is then added to vaddr
before returning. It also moves vm_map_region() and vm_unmap_region()
to vm_region.c.
Signed-off-by: Yanfeng Liu <yfliu2008@qq.com>