RISC-V: KVM: Add separate source for forwarded SBI extensions

Add a separate source vcpu_sbi_forward.c for SBI extensions
which are entirely forwarded to KVM user-space.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20251017155925.361560-3-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

arch/riscv/kvm/Makefile

@@ -27,6 +27,7 @@ kvm-y += vcpu_onereg.o
 kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_pmu.o
 kvm-y += vcpu_sbi.o
 kvm-y += vcpu_sbi_base.o
+kvm-y += vcpu_sbi_forward.o
 kvm-y += vcpu_sbi_fwft.o
 kvm-y += vcpu_sbi_hsm.o
 kvm-$(CONFIG_RISCV_PMU_SBI) += vcpu_sbi_pmu.o