nixos: Remove modprobe.d/nixos.conf from initrd.
nixos: Remove modprobe.d/nixos.conf from initrd.

For example in VM tests, this causes firmware to be included in the
initrd. So until we have a better fix for adding early-stage module
options, I'll remove this.

Fixes a regression introduced by 0aa2c1d and closes #3764.

Signed-off-by: aszlig <ee1aa092358634f9c53f01b5a783726c9e21b35a@redmoonstudios.org>

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