fb-tests: Prepend fb- to the binaries

The binaries conflict with perf and mesa-demos. Update do_install to
prefix the binaries, avoiding the namespace conflict.

Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Cc: Koen Kooi <koen@dominion.thruhere.net>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>