Fix TK gemmbench after renaming of tkw.reduction() to tkw.iterate() (#77)

See
iree-org/iree-turbine@5cee489

Author: andfau-amd

iree_kernel_benchmark/gemmbench/gemm_utils.py

@@ -247,7 +247,7 @@ def gemm(
 
         # This microkernel encodes the fact that if the reduction
         # dimension were tiled, then we would need to materialize a loop.
-        @tkw.reduction(K, init_args=[c_reg])
+        @tkw.iterate(K, init_args=[c_reg])
         def repeat(acc: tkl.Register[M, N, tkl.f32]) -> tkl.Register[M, N, tkl.f32]:
             # a_reg: tkw.Register[M, K, tkl.f16]
             a_reg = tkw.read(a, elements_per_thread=LOAD_ELEMS_PER_THREAD)