tcp_comp: Avoiding the null pointer problem of ctx in comp_stream_read

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I45UYC?from=project-issue


CVE: NA

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In comp_stream_read ctx might be null, add null check to avoid oops. And delete
unnecessary tcp_comp_err_abort.

Signed-off-by: Wang Yufen <wangyufen@huawei.com>
Reviewed-by: Yue Haibing <yuehaibing@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>