arm64: Improve parking of stopped CPUs

The current code puts the stopped cpus in an 'yield' instruction loop.
Using a busy loop here is unnecessary, we can use the cpu_park_loop()
function here to do a wfi/wfe.

Signed-off-by: Jayachandran C <jnair@caviumnetworks.com>
Signed-off-by: Aaro Koskinen <aaro.koskinen@nokia.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/kernel/smp.c

@@ -850,9 +850,7 @@ static void ipi_cpu_stop(unsigned int cpu)
 
 	local_daif_mask();
 	sdei_mask_local_cpu();
-
-	while (1)
-		cpu_relax();
+	cpu_park_loop();
 }
 
 #ifdef CONFIG_KEXEC_CORE