vmm: acpi: Take &T instead of &Arc<Mutex<T>>

Refactor ACPI table creation functions to accept borrowed
references, removing double indirection and moving locking
to callers.

Signed-off-by: Chinmoy <daschinmoyy21@gmail.com>

vmm/src/device_manager.rs

@@ -1756,7 +1756,7 @@ impl DeviceManager {
     }
 
     #[cfg(target_arch = "aarch64")]
-    pub fn get_interrupt_controller(&mut self) -> Option<&Arc<Mutex<gic::Gic>>> {
+    pub fn get_interrupt_controller(&self) -> Option<&Arc<Mutex<gic::Gic>>> {
         self.interrupt_controller.as_ref()
     }
 
@@ -1793,7 +1793,7 @@ impl DeviceManager {
     }
 
     #[cfg(target_arch = "riscv64")]
-    pub fn get_interrupt_controller(&mut self) -> Option<&Arc<Mutex<aia::Aia>>> {
+    pub fn get_interrupt_controller(&self) -> Option<&Arc<Mutex<aia::Aia>>> {
         self.interrupt_controller.as_ref()
     }