radeon/vcn: set dec->bs_ptr = NULL on unmap

To avoid using a dangling pointer.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/1308
Cc: mesa-stable
Reviewed-by: Boyuan Zhang <boyuan.zhang@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6556>
2 files changed