drm/nouveau: remove incorrect __user annotations

Fix copy-paste error causing EXEC and VM_BIND syscalls data pointers
to carry incorrect __user annotations.

Fixes: b88baab8 ("drm/nouveau: implement new VM_BIND uAPI")
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230807163238.2091-4-dakr@redhat.com