tools: Check for missing newlines in text files

The CI will now check whether any text files are missing
newlines at the EOF as this would make them incorrect
text files under Unix and hence some Unix utilities would
have an undesired behaviour on those files.

Signed-off-by: Tomás Agustín González Orlando <tomasagustin.gonzalezorlando@arm.com>
Change-Id: If9477d49b1b8543bb30bdd128b091a437ca92f69