Remove the unnecessary smp_wmb(), which was added to make sure
that the update_cpu_boot_status() completes before we mark the
CPU online. But update_cpu_boot_status() already has dsb() (required
for the failing CPUs) to ensure the correct behavior.
Cc: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Reported-by: Dennis Chen <dennis.chen@arm.com> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>