arm64: smp: Handle errors reported by the firmware

The __cpu_up() routine ignores the errors reported by the firmware
for a CPU bringup operation and looks for the error status set by the
booting CPU. If the CPU never entered the kernel, we could end up
in assuming stale error status, which otherwise would have been
set/cleared appropriately by the booting CPU.
Reported-by: Steve Capper <steve.capper@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/smp.c

@@ -141,6 +141,7 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
 		}
 	} else {
 		pr_err("CPU%u: failed to boot: %d\n", cpu, ret);
+		return ret;
 	}
 
 	secondary_data.task = NULL;