kasan: test: Use NULL macros

Replace PTR_EQ checks with the more idiomatic and specific NULL macros.
Acked-by: Daniel Latypov <dlatypov@google.com>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Acked-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

lib/test_kasan.c

@@ -391,7 +391,7 @@ static void krealloc_uaf(struct kunit *test)
 	kfree(ptr1);
 
 	KUNIT_EXPECT_KASAN_FAIL(test, ptr2 = krealloc(ptr1, size2, GFP_KERNEL));
-	KUNIT_ASSERT_PTR_EQ(test, (void *)ptr2, NULL);
+	KUNIT_ASSERT_NULL(test, ptr2);
 	KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)ptr1);
 }