drm/nouveau: pass cli to nouveau_channel_new() instead of drm+device

Both of these are stored in nouveau_cli already, and also allows the
removal of some void casts.

Signed-off-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240726043828.58966-32-bskeggs@nvidia.com