zynqmp: PSCI: Wait for FW completing wake requests

Powering up cores didn't wait for the PMUFW to complete the request,
which could result in cores failing to power up in Linux.
Reported-by: Koteswararao Nayudu <kotin@xilinx.com>
Signed-off-by: Soren Brinkmann <soren.brinkmann@xilinx.com>

plat/xilinx/zynqmp/plat_psci.c

@@ -104,7 +104,7 @@ static int zynqmp_pwr_domain_on(u_register_t mpidr)
 	proc = pm_get_proc(cpu_id);
 
 	/* Send request to PMU to wake up selected APU CPU core */
-	pm_req_wakeup(proc->node_id, 1, zynqmp_sec_entry, REQ_ACK_NO);
+	pm_req_wakeup(proc->node_id, 1, zynqmp_sec_entry, REQ_ACK_BLOCKING);
 
 	return PSCI_E_SUCCESS;
 }