ARM: 7921/1: mcpm: remove redundant dsb instructions prior to sev

sync_cache_w already includes a dsb, so we can just use sev() directly
then following a cache-sync.
Acked-by: NDave Martin <Dave.Martin@arm.com>
Acked-by: NNicolas Pitre <nico@linaro.org>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/common/mcpm_entry.c

@@ -166,7 +166,7 @@ void __mcpm_cpu_down(unsigned int cpu, unsigned int cluster)
 	dmb();
 	mcpm_sync.clusters[cluster].cpus[cpu].cpu = CPU_DOWN;
 	sync_cache_w(&mcpm_sync.clusters[cluster].cpus[cpu].cpu);
-	dsb_sev();
+	sev();
 }
 
 /*
@@ -182,7 +182,7 @@ void __mcpm_outbound_leave_critical(unsigned int cluster, int state)
 	dmb();
 	mcpm_sync.clusters[cluster].cluster = state;
 	sync_cache_w(&mcpm_sync.clusters[cluster].cluster);
-	dsb_sev();
+	sev();
 }
 
 /*