drm/vmwgfx: Fix some memory leaks on errors

Dan noticed some issues with pci_release_region, this builds upon
that and fixes some other lingering issues. As part of this we
also can stop trying to manually free our managed device;
there's no need for it, it will be cleaned up automatically for us.

Fixes: 8772c0bb ("drm/vmwgfx: Cleanup pci resource allocation")
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210128173756.121525-1-zackr@vmware.com