tee: fix compiler warning in teeshmregister()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.15.68 by commit e2ec1064a47dea9ea8e405c03307ad438ead2095, it was introduced in version v5.15.62 by commit c12f0e6126ad223806a365084e86370511654bf1. For more details please see the references link.