[example] Upgrade mpm88 to new syntax (#1581)
[example] Upgrade mpm88 to new syntax (#1581)

* [skip ci] [example] Upgrade mpm88 to new syntax for easy-study

* [skip ci] fix ident
yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi,yuanming-hu/taichi