[test] Skip slow test on ppc64

TBR=mythria@chromium.org
NOTRY=true

Bug: v8:9246
Change-Id: I18d6c22da5746d3af34c65ea22fd5ef80e4f13fb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1622850Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61721}

test/mjsunit/mjsunit.status

@@ -917,7 +917,7 @@
   # Too slow for TSAN in stress mode.
   # Goes OOM on ODROID devices: https://crbug.com/v8/9026
   # Too slow on PPC: https://crbug.com/v8/9246
-  'es6/classes': [PASS, SLOW, ['tsan or (arch == arm and not simulator_run) or arch == ppc', SKIP]],
+  'es6/classes': [PASS, SLOW, ['tsan or (arch == arm and not simulator_run) or arch in [ppc, ppc64]', SKIP]],
   'regress/regress-1122': [PASS, ['tsan', SKIP]],
 
   # Too slow with gc_stress on arm64.