staging: ion: Prevent incorrect reference counting behavour

stable inclusion
from stable-v5.10.113
commit fea24b07edfc348c67a019b6e17b39c0698e631f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ISAH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fea24b07edfc348c67a019b6e17b39c0698e631f



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Supply additional check in order to prevent unexpected results.

Fixes: b892bf75 ("ion: Switch ion to use dma-buf")
Suggested-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>