hypervisor: cpu: Fix get/set one reg error message

The error message of `SetRegister` and `GetRegister` fail to describe
the reason as the error variant suggests. Fixed error message
accordingly.

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

hypervisor/src/cpu.rs

@@ -165,12 +165,12 @@ pub enum HypervisorCpuError {
     ///
     /// Setting one reg error
     ///
-    #[error("Failed to init vcpu: {0}")]
+    #[error("Failed to set one reg: {0}")]
     SetRegister(#[source] anyhow::Error),
     ///
     /// Getting one reg error
     ///
-    #[error("Failed to init vcpu: {0}")]
+    #[error("Failed to get one reg: {0}")]
     GetRegister(#[source] anyhow::Error),
     ///
     /// Getting guest clock paused error