[vm/benchmark] Fix metric type of GenKernelKernelMaxRSS benchmark

Change-Id: Id7d0cdea5536752217968e235d065ce9b0140443
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/151307
Auto-Submit: Alexander Aprelev <[email protected]>
Commit-Queue: Ryan Macnak <[email protected]>
Reviewed-by: Ryan Macnak <[email protected]>

Author: aam

runtime/vm/benchmark_test.cc

@@ -180,7 +180,7 @@ BENCHMARK(GenKernelKernelCombined) {
                                /* benchmark_read_bytecode */ true));
 }
 
-BENCHMARK(GenKernelKernelMaxRSS) {
+BENCHMARK_MEMORY(GenKernelKernelMaxRSS) {
   GenKernelKernelBenchmark("GenKernelKernelMaxRSS benchmark",
                            /* benchmark_load */ false,
                            /* benchmark_read_bytecode */ true);