riscv64 has no "other" to need an sepolicy.

Fixes
```
out/soong/installs-aosp_riscv64.mk:56833: error: overriding commands for target `out/target/product/generic_riscv64/system/etc/seccomp_policy/crash_dump.riscv64.policy', previously defined at out/soong/installs-aosp_riscv64.mk:56829
```

Test: m
Change-Id: I78a1c6b10dac2da704515f33b492ff37cc086dd6