Re-enable the loading.mobile benchmark

TBR=toyoshim@chromium.org
NOTRY=true

Bug: 966624
Change-Id: I9428e8b686498f46c7c15ad75e83b08ad996a6c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636261Reviewed-by: Caleb Rouleau <crouleau@chromium.org>
Commit-Queue: Caleb Rouleau <crouleau@chromium.org>
Cr-Commit-Position: refs/heads/master@{#664962}

tools/perf/expectations.config

@@ -190,7 +190,6 @@ crbug.com/865400 [ Pixel2_Webview ] loading.mobile/Hongkiat_3g [ Skip ]
 crbug.com/865400 [ Pixel2_Webview ] loading.mobile/OLX_3g [ Skip ]
 crbug.com/865400 [ Pixel2_Webview ] loading.mobile/VoiceMemos_cold_3g [ Skip ]
 crbug.com/919191 [ Nexus5X_Webview ] loading.mobile/OLX_3g [ Skip ]
-crbug.com/966624 [ Pixel_2 ] loading.mobile/* [ Skip ] # mass disabling to set up the bot for pixel 2
 
 # Benchmark: oilpan_gc_times.key_silk_cases
 crbug.com/446332 [ All ] oilpan_gc_times.key_silk_cases/slide_drawer [ Skip ]