media: renesas: vsp1: Fix NULL pointer deref on module unload

In the Linux kernel, the following vulnerability has been resolved:

media: renesas: vsp1: Fix NULL pointer deref on module unload

When unloading the module on gen 4, we hit a NULL pointer dereference.

This is caused by the cleanup code calling vsp1_drm_cleanup() where it

should be calling vsp1_vspx_cleanup().

Fix this by checking the IP version and calling the drm or vspx function

accordingly, the same way as the init code does.