drm/nouveau: pass drm to nouveau_mem_new(), instead of cli

The nouveau_cli pointer is only ever used to eventually access
nouveau_drm, so just store it directly.

Signed-off-by: Ben Skeggs <bskeggs@nvidia.com>
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20240726043828.58966-30-bskeggs@nvidia.com