[Telemetry] Make memory benchmark enable/disables match old master.cfg.

tools/perf/benchmarks/memory.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from measurements import memory
 import page_sets
 from telemetry import benchmark
 
 
+@benchmark.Enabled('android')
 class MemoryMobile(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.MobileMemoryPageSet
 
 
-@benchmark.Disabled('android')
+@benchmark.Disabled
 class MemoryTop25(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.Top25PageSet
 
 
-@benchmark.Disabled('android')
+@benchmark.Disabled
 class Reload2012Q3(benchmark.Benchmark):
   tag = 'reload'
   test = memory.Memory
   page_set = page_sets.Top2012Q3PageSet
 
 
-@benchmark.Disabled('android')  # crbug.com/371153
+@benchmark.Disabled  # crbug.com/371153
 class MemoryToughDomMemoryCases(benchmark.Benchmark):
   test = memory.Memory
   page_set = page_sets.ToughDomMemoryCasesPageSet