hypervisor: kvm: Expose create_standard_regs() for all architectures

The aarch64 unit tests make use of this.

Fixes commit 3645654c39

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>

hypervisor/src/kvm/mod.rs

@@ -1207,7 +1207,6 @@ impl cpu::Vcpu for KvmVcpu {
     ///
     /// Returns StandardRegisters with default value set
     ///
-    #[cfg(target_arch = "x86_64")]
     fn create_standard_regs(&self) -> StandardRegisters {
         kvm_bindings::kvm_regs::default().into()
     }