Created by: zhaoyuchen2018

• Improve argsort performance.

• Give 200000 data to compute argsort on v100, can speed up ~190x before opt cost: 0.53s after opt cost:0.0027s

• Add fp16 support

• Refine error message
• Refine code
• Add descending sort

test=develop

Signed-off-by: zhaoyuchen zhaoyuchen01@baidu.com