lava_wait_jobs.py: Clarify retry message

Previous message was rather unclear, print(exc) prints "internal"
argument(s) of an exception, but not even a type of the exception,
so there could be output like:

19:23:45  'PsaApiTest_Crypto'

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I8ea8b2580276039d388d9244f6438556c21923a6
1 file changed