yuzu/bootmanager: Replace unnnecessary constructor initializer list member of GGLContext

The default constructor will always run, even when not specified, so
this is redundant.

However, the context member can indeed be initialized in the constructor
initializer list.

src/yuzu/bootmanager.cpp

@@ -91,8 +91,8 @@ void EmuThread::run() {
 
 class GGLContext : public Core::Frontend::GraphicsContext {
 public:
-    explicit GGLContext(QOpenGLContext* shared_context) : surface() {
-        context = std::make_unique<QOpenGLContext>(shared_context);
+    explicit GGLContext(QOpenGLContext* shared_context)
+        : context{std::make_unique<QOpenGLContext>(shared_context)} {
         surface.setFormat(shared_context->format());
         surface.create();
     }