fix int value compare issue when check memory size
fix int value compare issue when check memory size

return output is string type, can not compare with int type

for https://github.com/zxwing/premium/issues/1935

Signed-off-by: Mei Lei <d1c6e4e75080176552ef8271b379adabccaa7551@gmail.com>

zstackio/zstack-utility,zstackorg/zstack-utility,mingjian2049/zstack-utility,mrwangxc/zstack-utility,mrwangxc/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility,mingjian2049/zstack-utility,live4thee/zstack-utility,mrwangxc/zstack-utility,live4thee/zstack-utility,zstackorg/zstack-utility,zstackorg/zstack-utility,mingjian2049/zstack-utility,live4thee/zstack-utility