Remove test reference files that are not generated any more:
* chair.cook.ppm: This file should be generated by eon and not
mcf, so it shouldn't be included as an output from mcf.
* system.pc.terminal: The terminal device has been renamed so this
file is no longer generated.
Change-Id: I3962efe1ff25479ca276115f7564eccb5fac8cf9
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>