hypervisor: cpu: Fix GetRegList comment

`GetRegList` variant will be referenced on both Aarch and RISC-V. Fixed
comment to generalize this error variant.

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

hypervisor/src/cpu.rs

@@ -217,7 +217,7 @@ pub enum HypervisorCpuError {
     #[error("Failed to set aarch64 core register: {0}")]
     SetAarchCoreRegister(#[source] anyhow::Error),
     ///
-    /// Getting AArch64 registers list error
+    /// Getting registers list error
     ///
     #[error("Failed to retrieve list of registers: {0}")]
     GetRegList(#[source] anyhow::Error),