During the module initialization phase, entropy will be added
to entropy pool for every interrupt, the change should speed up
initialization of the random module.

Before optimization:
[   22.180236] random: crng init done

After optimization:
[    1.474832] random: crng init done
Signed-off-by: NXingjun Liu <xingjun.lxj@alibaba-inc.com>
Reviewed-by: NLiu Jiang <gerry@linux.alibaba.com>
Reviewed-by: NCaspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Jia Zhang <zhang.jia@linux.alibaba.com>
Reviewed-by: NYang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: NLiu Bo <bo.liu@linux.alibaba.com>