drm/radeon: update the VM after setting BO address v4

This way the necessary VM update is kicked off immediately
if all BOs involved are in GPU accessible memory.

v2: fix vm lock
v3: immediately update unmaps as well
v4: use drm_free_large instead of kfree

Tested-by: Kai Wasserbäch <kai@dev.carbon-project.org>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>