test_096_boot_symbols_unreadable failed on B-hwe PowerPC

Even with bug 1843327 fixed.

This test is still failing on Bionic 5.0 PowerPC (passed on amd64 / i386 / arm64)

  ======================================================================
  FAIL: test_096_boot_symbols_unreadable (__main__.KernelSecurityTest)
  kernel addresses in /boot are not world readable
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "./test-kernel-security.py", line 1438, in test_096_boot_symbols_unreadable
      self.assertEqual(os.stat(name).st_mode & mask, expected, '%s is world readable' % (name))
  AssertionError: /boot/vmlinux-5.0.0-34-generic is world readable

  ----------------------------------------------------------------------
  Ran 125 tests in 38.316s

ubuntu@baltar:~$ ll /boot/vmlinux-5.0.0-34-generic
-rw-rw-r-- 1 root root 26176593 Oct 30 06:22 /boot/vmlinux-5.0.0-34-generic

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: linux-image-5.0.0-34-generic 5.0.0-34.36~18.04.1
ProcVersionSignature: Ubuntu 5.0.0-34.36~18.04.1-generic 5.0.21
Uname: Linux 5.0.0-34-generic ppc64le
ApportVersion: 2.20.9-0ubuntu7.9
Architecture: ppc64el
Date: Wed Nov 6 10:45:59 2019
ProcLoadAvg: 0.33 0.20 0.09 1/1363 9722
ProcLocks:
 1: FLOCK ADVISORY WRITE 3474 00:17:516 0 EOF
 2: POSIX ADVISORY WRITE 3902 00:17:597 0 EOF
 3: POSIX ADVISORY WRITE 4117 00:17:605 0 EOF
 4: POSIX ADVISORY WRITE 1820 00:17:380 0 EOF
 5: FLOCK ADVISORY WRITE 3895 00:17:588 0 EOF
ProcSwaps:
 Filename Type Size Used Priority
 /swap.img file 8388544 0 -2
ProcVersion: Linux version 5.0.0-34-generic (buildd@bos02-ppc64el-010) (gcc version 7.4.0 (Ubuntu 7.4.0-1ubuntu1~18.04.1)) #36~18.04.1-Ubuntu SMP Wed Oct 30 08:07:02 UTC 2019
SourcePackage: linux-signed-hwe
UpgradeStatus: No upgrade log present (probably fresh install)
VarLogDump_list: total 0
cpu_cores: Number of cores present = 40
cpu_coreson: Number of cores online = 39
cpu_dscr: DSCR is 16
cpu_freq:
 min: 2.862 GHz (cpu 79)
 max: 2.945 GHz (cpu 81)
 avg: 2.903 GHz
cpu_runmode:
 Could not retrieve current diagnostics mode,
 No kernel interface to firmware
cpu_smt: SMT=4