nv-interface is linked but not needed

[Dimitri John Ledkov]

grep nv-interface.o -r .
./CLEAN:rm -f nvidia/nv-interface.o
./BUILD:/usr/bin/ld.bfd -r -o nvidia/nv-interface.o nvidia/nv.o nvidia/nv-pci.o nvidia/nv-acpi.o nvidia/nv-cray.o nvidia/nv-dma.o nvidia/nv-i2c.o nvidia/nv-mmap.o nvidia/nv-p2p.o nvidia/nv-pat.o nvidia/nv-procfs.o nvidia/nv-procfs-utils.o nvidia/nv-usermap.o nvidia/nv-vm.o nvidia/nv-vtophys.o nvidia/os-interface.o nvidia/os-mlock.o nvidia/os-pci.o nvidia/os-registry.o nvidia/os-usermap.o nvidia/nv-modeset-interface.o nvidia/nv-pci-table.o nvidia/nv-kthread-q.o nvidia/nv-memdbg.o nvidia/nv-ibmnpu.o nvidia/nv-report-err.o nvidia/nv-rsync.o nvidia/nv-msi.o nvidia/nv-caps.o nvidia/nv-frontend.o nvidia/nv_uvm_interface.o nvidia/nvlink_linux.o nvidia/nvlink_caps.o nvidia/linux_nvswitch.o nvidia/procfs_nvswitch.o nvidia/i2c_nvswitch.o

Note that nvidia/nv-interface.o is created, but not used by any modules.

In the kbuild we have:

#
# Build nv-interface.o from the kernel interface layer objects, suitable
# for further processing by the top-level makefile to produce a precompiled
# kernel interface file.
#

NVIDIA_INTERFACE := nvidia/nv-interface.o

# Linux kernel v5.12 and later looks at "always-y", Linux kernel versions
# before v5.6 looks at "always"; kernel versions between v5.12 and v5.6
# look at both.

always += $(NVIDIA_INTERFACE)
always-y += $(NVIDIA_INTERFACE)

$(obj)/$(NVIDIA_INTERFACE): $(addprefix $(obj)/,$(NVIDIA_OBJECTS))
        $(LD) -r -o $@ $^

But i'm not sure if we actually do any further processing, or use precompiled kernel interface file.