RISC-V: KVM: Allow Zimop extension for Guest/VM

RISC-V: KVM: Allow Zimop extension for Guest/VM

Extend the KVM ISA extension ONE_REG interface to allow KVM user space
to detect and enable Zimop extension for Guest/VM.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Acked-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20240619113529.676940-5-cleger@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>