test/log: fix dynamic log levels testing

test/log: fix dynamic log levels testing

This patch fixes the dynamic log levels testing in logs_autotest.
Introduction of rte_log_set_level() in patch c1b5fa94a46f was done
with parameter RTE_LOG_EMERG which caused all RTE_LOG() calls an
early return due to all given levels were far below EMERG.
If first two logs supposed to show up on console, the initial log
level must be low (DEBUG). It is than changed above ERR when we test
if TESTAPP2 log type can be filtered by log type log level.

Fixes: c1b5fa94a46f ("eal: support dynamic log types")

Signed-off-by: Radoslaw Biernacki <radoslaw.biernacki@linaro.org>
Acked-by: Olivier Matz <olivier.matz@6wind.com>