igt/gem_mocs_settings: Skip non-existent engines

For per-engine checks, check the engine actually exists (important for
bsd aliasing).

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=101905
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: MichaƂ Winiarski <michal.winiarski@intel.com>
1 file changed