drm/vmwgfx: Split GMR2_REMAP commands if they are to large

This fixes the piglit test texturing/max-texture-size
causing the VM to die due to a too large SVGA command.

Signed-off-by: Jakob Bornecrantz <jakob@vmware.com>
Reviewed-by: Biran Paul <brianp@vmware.com>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dave Airlie <airlied@gmail.com>