csky/smp: Fixup boot failed when CONFIG_SMP

[ Upstream commit c9492737 ]

If we use a non-ipi-support interrupt controller, it will cause panic here.
We should let cpu up and work with CONFIG_SMP, when we use a non-ipi intc.

Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>