powerpc: hard_irq_disable(): Call trace_hardirqs_off after disabling

lockdep.c has this:
        /*
         * So we're supposed to get called after you mask local IRQs,
         * but for some reason the hardware doesn't quite think you did
         * a proper job.
         */
	if (DEBUG_LOCKS_WARN_ON(!irqs_disabled()))
		return;

Since irqs_disabled() is based on soft_enabled(), that (not just the
hard EE bit) needs to be 0 before we call trace_hardirqs_off.

Signed-off-by: Scott Wood <scottwood@freescale.com>