drm/vmwgfx: Move surface copy cmd to atomic function

When display surface is different than the framebuffer surface, atomic
path do not copy the surface data. This commit moved the code to copy
surface from legacy to atomic path.

Signed-off-by: Deepak Rawat <drawat@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>