v3dv/pipeline_cache: bail out in case of error
Currently, in GetPipelineCacheData() function, in several cases if
there is an error the blob is finished and cache unlocked, but code
continues executing, which can lead to multiple
pthread_mutex_unlock()
calls.
Instead, if there's an error just bail out to finish the blob and unlock the cache directly.
Fixes CID#1468147 "Double unlock (LOCK)".