sw64: restart idle routine if it is interrupted

Sunway inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I73O8F



--------------------------------

If need_resched() or HALT instruction is interrupted, restart from
need_resched() so we won't miss schedule request.

Signed-off-by: Mao Minkai <maominkai@wxiat.com>
Reviewed-by: He Sheng <hesheng@wxiat.com>
Signed-off-by: Gu Zitao <guzitao@wxiat.com>