ltp: don't fail test suite when losing device connection

Terminating after loss of device appears to be too strict; checking for
root permission is probably sufficient.

Bug: 368144215
Bug: 402299150
Test: atest vts_ltp_test_arm_64
Change-Id: I9d8fe89ce823e350ec24c8e52c0c573c6b84c4ac
Signed-off-by: Edward Liaw <edliaw@google.com>