It makes no sense to initialize the mpic ipi for the SoC which has
doorbell support. So set the smp_85xx_ops.probe to NULL for this
case. Since the smp_85xx_ops.probe is also used in function
smp_85xx_setup_cpu() to check if we need to invoke
mpic_setup_this_cpu(), we introduce a new setup_cpu function
smp_85xx_basic_setup() to remove this dependency.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>