* add gpt2 test on XPU Signed-off-by: jiqing-feng <jiqing.feng@intel.com> * auto dtype has been fixed Signed-off-by: jiqing-feng <jiqing.feng@intel.com> * convert model to train mode Signed-off-by: jiqing-feng <jiqing.feng@intel.com> --------- Signed-off-by: jiqing-feng <jiqing.feng@intel.com>