ci: travis: keep only code rule checks
ci: travis: keep only code rule checks

The Travis build keeps timing out apparently due to a reduced download
speed compared with some time ago. It is not rare for the build to fail
in the initial "repo sync" phase with the error message:

 No output has been received in the last 10m0s, this potentially
 indicates a stalled build or something wrong with the build itself.

Allowing more verbosity from "repo sync" could possibly avoid this
particular error, but then the second issue is that total build time
reaches 50 minutes very frequently which is the limit for Open Source
projects.

Since we have IBART to run xtest on HiKey, we can loose the test on
QEMU. Therefore, this commit keeps only the code rule checks in the
Travis script (checkpatch.pl and pycodestyle).

Signed-off-by: Jerome Forissier <ced78d268b4c9a0a20a59a9feeebd2ad90da03d3@linaro.org>
Reviewed-by: Joakim Bech <741f90e2a7f4d9afbad8bd50be20560f4cf38962@linaro.org>

pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os,pascal-brand-st-dev/optee_os