Disabling smoothness.touch_pinch_zoom_cases on all platforms due to red bots

BUG=631015
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.perf:android_s5_perf_cq;master.tryserver.chromium.perf:linux_perf_cq;master.tryserver.chromium.perf:mac_retina_perf_cq;master.tryserver.chromium.perf:winx64_10_perf_cq

Review-Url: https://codereview.chromium.org/2177203003
Cr-Commit-Position: refs/heads/master@{#407625}

tools/perf/benchmarks/smoothness.py

@@ -283,7 +283,7 @@ class SmoothnessSimpleMobilePages(_Smoothness):
     return 'smoothness.simple_mobile_sites'
 
 
-@benchmark.Enabled('android')
+@benchmark.Disabled('all') # http://crbug.com/631015
 class SmoothnessToughPinchZoomCases(_Smoothness):
   """Measures rendering statistics for pinch-zooming in the tough pinch zoom
   cases.