lib/trusty: tipc-test should not print results to error stream

tipc-test results cannot be parsed in the CI because they output to
error stream

Bug: 314130383
Test: /data/nativetest64/vendor/tipc-test/tipc-test -t echo -r 1 -B 100
Change-Id: I2d6506fd69af06338041035526ca759884719c7b