nouveau/dmem: Fix privileged error in copy engine channel

When `nouveau_dmem_copy_one` is called, the following error occurs:

[272146.675156] nouveau 0000:06:00.0: fifo: PBDMA9: 00000004 [HCE_PRIV]
ch 1 00000300 00003386

This indicates that a copy push command triggered a Host Copy Engine
Privileged error on channel 1 (Copy Engine channel). To address this
issue, modify the Copy Engine channel to allow privileged push commands

Fixes: 6de12538 ("drm/nouveau/fifo: expose runlist topology info on all chipsets")
Signed-off-by: Yonatan Maman <Ymaman@Nvidia.com>
Co-developed-by: Gal Shalom <GalShalom@Nvidia.com>
Signed-off-by: Gal Shalom <GalShalom@Nvidia.com>
Reviewed-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241008115943.990286-2-ymaman@nvidia.com