examples: Unify the example target's name with its directory

In some SDK examples, there is a mismatch between their
Cmake target name and the directory of the example.
These changes improve this. The example target contains
the full name of its directory.

This will standardize the naming of the examples and
facilitate the creation of scripts for building and running
examples.

Signed-off-by: Artur Tynecki <artur.tynecki@arm.com>