wakeup stats: ignore /sys/class/wakeup/.../device symlink

This symlink points to the sysfs hierarchy of the device that owns the
wakeup source, if the latter is not virtual.

That symlink is of no interst to us. Make system suspend not read that
directory to avoid spamming SELinux denial log, e.g.

avc: denied { open } for comm="Binder:1790_2"
path="/sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A03:00/device:04"
dev="sysfs" ino=2157 scontext=u:r:system_suspend:s0
tcontext=u:object_r:sysfs:s0 tclass=dir permissive=1

Bug: 144095608
Test: SystemSuspendV1_0UnitTest
Change-Id: I8ede20d6233b8c8a051b57ee9a0c433abc47fdf4
1 file changed