trusty_driver_test: Scan for new device sysfs paths

The FF-A changes add new names for the Trusty devices
(trusty-ffa and trusty-core) and expand the device hierarchy.

See https://r.android.com/3369480 and https://r.android.com/3368602
for the corresponding changes to the Trusty test-map.

Bug: 284057071
Test: adb sync data && trusty_driver_test.py
Change-Id: I509cf3a78214c3cf4a54727cc6c8d057ae2257ad