misc: Remove redundant "use" imports

With the nightly toolchain (2024-02-18) cargo check will flag up
redundant imports either because they are pulled in by the prelude on
earlier match.

Remove those redundant imports.

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

hypervisor/src/arch/x86/emulator/mod.rs

@@ -651,10 +651,8 @@ mod mock_vmm {
     #![allow(unused_mut)]
 
     use super::*;
-    use crate::arch::emulator::{EmulationError, PlatformEmulator};
-    use crate::arch::x86::emulator::{Emulator, EmulatorCpuState as CpuState};
+    use crate::arch::x86::emulator::EmulatorCpuState as CpuState;
     use crate::arch::x86::gdt::{gdt_entry, segment_from_gdt};
-    use crate::arch::x86::Exception;
     use std::sync::{Arc, Mutex};
 
     #[derive(Debug, Clone)]