Fix sampler lifecycle

- Add refcount to sampler to avoid use after free

Change-Id: I0f03d8ed29b5b9dc5bee355ed266ac7437e92509

unit_tests/accelerators/media_image_arg_tests.cpp

@@ -80,9 +80,9 @@ class MediaImageSetArgTest : public DeviceFixture,
     }
 
     void TearDown() override {
-        delete pKernelInfo;
         delete srcImage;
         delete pKernel;
+        delete pKernelInfo;
         delete context;
         DeviceFixture::TearDown();
     }