blackfin: smp: cleanup smp code

move idle task point to percpu blackfin_cpudata and add smp_timer_broadcast
interface.
enable SUPPLE_1_WAKEUP and add BFIN_IPI_TIMER ipi support.

Signed-off-by: Steven Miao <realmz6@gmail.com>
Signed-off-by: Bob Liu <lliubbo@gmail.com>