etnaviv: Fix memory leak on error path.
Fix warning reported by Coverity Scan.
Resource leak (RESOURCE_LEAK)
leaked_storage: Variable pq going out of scope leaks the storage it
points to.
Fixes: eed5a009897a ("etnaviv: convert perfmon queries to acc queries")
Signed-off-by: Vinson Lee <vlee@freedesktop.org>
cc: @austriancoder