spapr: fix leak of rev array

Introduced in 04d595b300 ("spapr: do not use CPU_FOREACH_REVERSE",
2018-08-23)

Fixes: CID1395181
Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

hw/ppc/spapr.c

@@ -607,6 +607,7 @@ static void spapr_populate_cpus_dt_node(void *fdt, sPAPRMachineState *spapr)
         spapr_populate_cpu_dt(cs, fdt, offset, spapr);
     }
 
+    g_free(rev);
 }
 
 static uint32_t spapr_pc_dimm_node(MemoryDeviceInfoList *list, ram_addr_t addr)