init: support matching sysfs class paths in ueventd.rc

Currently, ueventd.rc files only support /sys/devices/... paths
and don't support symlinked paths, specifically /sys/class/...
Supporting the class paths is necessary to have non-hardware
dependent paths. Some subsystems like IIO use /sys/bus/iio/, so
support that as well.

Change-Id: I29f3bf67b41664d1d75ac1820c46e13afe336d56
Signed-off-by: Rob Herring <robh@kernel.org>