Fix unused variable warning in adagrad_fused_op_gpu.cu (#71556)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/71556
Test Plan: Sandcastle
Reviewed By: jspark1105
Differential Revision: D33675154
fbshipit-source-id: f5ce981f5e7d3351be225d22156070bf2a7ed2b3
(cherry picked from commit 7409c02b4f685e2e1881cd2cfb627adf8ebc13cb)
