hypervisor: x86: emulator: Remove unncessary mut from reference

warning: this argument is a mutable reference, but not used mutably
  --> hypervisor/src/arch/x86/emulator/instructions/mod.rs:22:15
   |
22 |     platform: &mut dyn PlatformEmulator<CpuState = T>,
   |               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider changing to: `&dyn PlatformEmulator<CpuState = T>`
   |
   = note: this is cfg-gated and may require further changes
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_pass_by_ref_mut

Signed-off-by: Rob Bradford <rbradford@rivosinc.com>
(cherry picked from commit 239f422203)

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

@@ -18,8 +18,8 @@ fn get_op<T: CpuStateManager>(
     insn: &Instruction,
     op_index: u32,
     op_size: usize,
-    state: &mut T,
-    platform: &mut dyn PlatformEmulator<CpuState = T>,
+    state: &T,
+    platform: &dyn PlatformEmulator<CpuState = T>,
 ) -> Result<u64, PlatformError> {
     if insn.op_count() < op_index + 1 {
         return Err(PlatformError::InvalidOperand(anyhow!(