drm/lima: add lima_vm_map_bo

For dynamically mapping added backup memory of lima_bo to vm.
This is a preparation for adding heap buffer support.

Reviewed-by: Vasily Khoruzhick <anarsoul@gmail.com>
Tested-by: Andreas Baierl <ichgeh@imkreisrum.de>
Signed-off-by: Qiang Yu <yuq825@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200116131157.13346-3-yuq825@gmail.com