fix legacy GET_BLOCKS code from THCUNN/common.h (#44789)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/44472
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44789
Reviewed By: malfet
Differential Revision: D23732762
Pulled By: walterddr
fbshipit-source-id: c3748e365e9a1d009b00140ab0ef892da905d09b
