mm/sharepool: Delete total_num and total_size in sp_spa_stat

hulk inclusion
category: other
bugzilla: https://gitee.com/openeuler/kernel/issues/I6GI0X



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total_num and total_size in sp_spa_stat is redundant,
they can be calculated, so delete them.

Signed-off-by: Xu Qiang <xuqiang36@huawei.com>