Kernel/VirtIO: Improve error handling during device initialization

Rename the initialize method to initialize_virtio_resources so it's
clear what this method is intended for.

To ensure healthier device initialization, we could also return the type
of ErrorOr<void> from this method, so in all overriden instances and in
the original method code, we could leverage TRY() pattern which also
does simplify the code a bit.

Kernel/Bus/VirtIO/RNG.h

@@ -24,7 +24,7 @@ public:
     virtual StringView device_name() const override { return class_name(); }
     virtual ~RNG() override = default;
 
-    virtual void initialize() override;
+    virtual ErrorOr<void> initialize_virtio_resources() override;
 
 private:
     virtual StringView class_name() const override { return "VirtIORNG"sv; }