Add zicboz support for riscv kvmtool

[Ben Dooks]

This is two simple patches, the first to sync the defines to ensure
that the struct kvm_riscv_config is sync with upstream and the second
to allow zicboz support into the guest.

[PATCH kvmtool 1/2] riscv: add mvendorid/marchid/mimpid to sync
[PATCH kvmtool 2/2] riscv: add zicboz support