When ddraw_texture_init needs to clean up on failure, it will call the
wined3d_texture_get_sub_resource_parent function on draw_texture in
order to retrieve its parent for a IDirectDrawSurface release call.
However, if draw_texture is NULL, then the function call will crash
due to a null pointer dereference.

Therefore, on failure cleanup, the release operation on the texture
parent should only be performed if draw_texture is not NULL.

This fixes a crash in the Virtual Insanity game demo.