CVE-2025-21824 gpu: host1x: Fix a use of uninitialized mutex

In the Linux kernel, the following vulnerability has been resolved: gpu: host1x: Fix a use of uninitialized mutex commit c8347f915e67 "gpu: host1x: Fix boot regression for Tegra" caused a use of uninitialized mutex leading to below warning when CONFIGDEBUGMUTEXES and CONFIGDEBUGLOCKALLOC are...