combine loops so fn_name correct in error message (#121601)
The error message shown when input aliasing is detected in `while_loop_func` may not have the correct `fn_name` as it set only in the previous for loop. This change merges the two loops so that `fn_name` has the correct value.
No Issue Number for this minor change.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/121601
Approved by: https://github.com/albanD
