Kernel/Graphics: Only search for PCI graphics cards on x86_64

This is for the upcoming commit that merges the x86_64 and aarch64
init.cpp files.

Kernel/Graphics/GraphicsManagement.cpp

@@ -223,6 +223,7 @@ UNMAP_AFTER_INIT bool GraphicsManagement::initialize()
  return true;
  }
 
+#if ARCH(X86_64)
  if (PCI::Access::is_disabled()) {
  dmesgln("Graphics: Using an assumed-to-exist ISA VGA compatible generic adapter");
  return true;
@@ -237,6 +238,7 @@ UNMAP_AFTER_INIT bool GraphicsManagement::initialize()
  if (auto result = determine_and_initialize_graphics_device(device_identifier); result.is_error())
  dbgln("Failed to initialize device {}, due to {}", device_identifier.address(), result.error());
  }));
+#endif
 
  // Note: If we failed to find any graphics device to be used natively, but the
  // bootloader prepared a framebuffer for us to use, then just create a DisplayConnector