benchmark/sys_kernel: use TC_PRINT_RUNID

For automation to detect this is the right test case being executed,
print the RUNID if defined

This TC doesn't use TC_*() macros, so we need to invoke it manually.

Change-Id: I6f7417621d649a59412bb92d8b665130757d926a
Signed-off-by: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>