CVE-2024-50284 ksmbd: Fix the missing xa_store error check

In the Linux kernel, the following vulnerability has been resolved: ksmbd: Fix the missing xastore error check xastore can fail, it return xaerr-EINVAL if the entry cannot be stored in an XArray, or xaerr-ENOMEM if memory allocation failed, so check error for xastore to fix it...