testcases: add automation markup to samples/

Code in samples does not follow an standarized format for reporting
success or operation failure -- thus we use markup (in file sample.tc)
to specify what shall be found in the console to consider execution a
success.

There is a few functional code modifications that add/extend console
messages so verification is possible or easier:

 - hello_world, synchronization: extend the success message to also
   print which core is running the testcase

- pci_enum: print message on success.

Change-Id: Idb6cea03adebe97d97854603f963f4e3d4cb856a
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>