dm: cache: Add enable and disable ops for sandbox and test

Add cache enable and disable ops for test coverage.

Signed-off-by: Rick Chen <rick@andestech.com>
Cc: KC Lin <kclin@andestech.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

test/dm/cache.c

@@ -14,6 +14,8 @@ static int dm_test_reset(struct unit_test_state *uts)
 
 	ut_assertok(uclass_get_device(UCLASS_CACHE, 0, &dev_cache));
 	ut_assertok(cache_get_info(dev, &info));
+	ut_assertok(cache_enable(dev));
+	ut_assertok(cache_disable(dev));
 
 	return 0;
 }