Allow dumpstate to read sysfs_loop files.

This prevents denials while taking a bugreport.

Bug: 116711254
Test: cts-tradefed run cts -m CtsSecurityHostTestCases -t
android.security.cts.SELinuxHostTest#testNoBugreportDenials

Change-Id: Ie190bfa62cf5aa172ebfff8bfd82dea2a7d1a016
diff --git a/public/dumpstate.te b/public/dumpstate.te
index cd3310a..1c8bbb1 100644
--- a/public/dumpstate.te
+++ b/public/dumpstate.te
@@ -90,6 +90,7 @@
 
 allow dumpstate {
   sysfs_dm
+  sysfs_loop
   sysfs_usb
   sysfs_zram
 }:file r_file_perms;