Add new perfmon capability2 and use it

There are probably more cases but this one blocks presubmit
for cuttlefish with mainline kernels.

Bug: 158304247
Change-Id: I6d769b16a230a113a804df61f8de4dcbce2193b6
diff --git a/private/access_vectors b/private/access_vectors
index 4144be8..f41eadd 100644
--- a/private/access_vectors
+++ b/private/access_vectors
@@ -138,6 +138,7 @@
 	wake_alarm
 	block_suspend
 	audit_read
+	perfmon
 }
 
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