Fix POLLHUP test in libpdx UDS transport tests.

UDS channel events require a translation call to determine the real
event mask that was signaled by the service. Add the correct
translation call to fix the test.

Bug: None
Test: build; push libpdx_uds_tests; run libpdx_uds_tests
Change-Id: I18f0a5dcaf7c507d72ed5226df1fe0e2c2e3dd98