Add uncrustify checks in JenkinsFile

[abhijit-mahajani-imgtec]

As mentioned in https://github.com/contiki-os/contiki/blob/master/CONTRIBUTING.md#code-formatting, we can add uncrustify checks either in git pre-commit hooks but still it would be better to have the check in Jenkinsfile too so that it gets caught in CI.

[Shpinkso]

Need some acceptance criteria in this ticket

[mtusnio]

Check here - https://github.com/CreatorDev/contiki/tree/3.0-mikro-e/tools/code-style - for all the tools to fix/check for issues. I think the acceptance criteria could be as follows:

• Fix all issues with uncrustify in the files we have changed in cpu/pic32 & platform/mikro-e
• Add uncrustify checks to the Jenkinsfile for any changed files in a PR