v3dv/bo: use mtx_lock/unlock on cache_init too

To handle coverity warning:
   4. thread2_modifies_field: Thread2 sets cache_size to a new value. Note that this write can be reordered at runtime to occur before instructions that do not access this field within this locked region. After Thread2 leaves the critical section, control is switched back to Thread1.
   CID 1559509 (#1 of 1): Check of thread-shared field evades lock acquisition (LOCK_EVASION)6. thread1_overwrites_value_in_field: Thread1 sets cache_size to a new value. Now the two threads have an inconsistent view of cache_size and updates to fields correlated with cache_size may be lost.
521   cache->cache_size += bo->size;

Reviewed-by: Juan A. Suarez <[email protected]>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26951>

Author: infapi00

src/broadcom/vulkan/v3dv_bo.c

@@ -419,9 +419,11 @@ v3dv_bo_cache_init(struct v3dv_device *device)
       fprintf(stderr, "MAX BO CACHE SIZE: %iMB\n", device->bo_cache.max_cache_size);
    }
 
+   mtx_lock(&device->bo_cache.lock);
    device->bo_cache.max_cache_size *= 1024 * 1024;
    device->bo_cache.cache_count = 0;
    device->bo_cache.cache_size = 0;
+   mtx_unlock(&device->bo_cache.lock);
 }
 
 void