riscv: Add pass(4) to GENERIC kernel

Whilst we don't have ahci(4) currently, we do have umass(4), and need
pass(4) for smartctl(8) to be able to talk to such devices.

Reported by: David Gilbert <dgilbert@daveg.ca>
MFC after: 1 week

(cherry picked from commit f78cc42f10cbfb5811276bc6827732ca32eb5485)