smartmontools: fix for its SysV init script

Changes include:
1. Make it run at runlevel 2, 3, 4 and 5 by default.
2. Add /etc/default/smartmontools, just as Ubuntu does.

Signed-off-by: Chen Qi <Qi.Chen@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>